I have a few questions, actually.

First, understanding the reproduction process of single celled organisms and how a single cell can copy itself without the aid of another cell, it is safe to assume that single celled organisms are asexual.  Correct? 
If that is the case, how is it that single celled organisms from "millions of years ago" jumbled themselves together to assume the multi-sexed creatures that require an act between the two to reproduce?

Second,  evolution is a theory and according to the definition of the word from dictionary.com a theory is "a proposed explanation whose status is still conjecture and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact."  In other words, "an idea, notion, or hypothesis." Why is it a "sin" in the scientific world to allow the teaching of all options to the origin of life, such as intelligent design, evolution, etc.?  Darwin didn't write the 'Origin of Life', he wrote 'The Origin of Species.'  To the extent that variations evolve from different kinds of animals, I believe this because it can be scientifically witnessed. (For example; dogs, cats, birds, bears, horses, etc.) Yet, the idea that life was came about by some random order of things, that molecules and atoms fell into place is highly improbable.  Couldn't the notion that there was a designer be concievable? Darwin himself stated that to say the complexity of the human eye was by accident is non-sense.

Kevin,

I am not an expert on the origins and development of multicellular life so I will leave that to others on this board. Responding to your second question is more up my alley.  

You wrote: "evolution is a theory and according to the definition of the word from dictionary.com a theory is "a proposed explanation whose status is still conjecture and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact."  In other words, "an idea, notion, or hypothesis.""

I went to dictionary.com and note that you selected the second of five definitions of the word 'theory'.  It's interesting that you chose the lighter, more colloquial definition. the one that is equivocated with "idea", and "notion".  You avoided the very first definition that is much more appropriate here.  I find that intellectually dishonest but will leave it at that.

I'll use the first definition because it's the definition used by scientists when they talk about a theory - "a coherent group of tested general propositions, commonly regarded as correct, that can be used as principles of explanation and prediction for a class of phenomena".  Note the first phrase that mentions a group of tested propositions.  That's the key to your whole set of questions.  In order for a theory to be scientific, it must be testable and for this reason, science cannot incorporate the supernatural.  The reason is simple.  Science relies on the assumption that there are rules that govern the universe.  The rules must be natural and regular.  If you introduce a supernatural force, you allow for those rules to be broken at the whim of that force.  That means that all tests of scientific hypotheses go out the window because if things don't make sense.  You can just throw up your hands and say, "the God/Intelligent Designer/Shiva/Jujumonkey that I belive in wanted it that way" to any experiment.  No, science MUST leave supernatural explanations out or it becomes meaningless.  

You wrote" "Why is it a "sin" in the scientific world to allow the teaching of all options to the origin of life, such as intelligent design, evolution, etc.?"

Would you recommend teaching East Asian Geography in a Mathematics class?  I hope you said "no".  It's not appropriate.  For the same reasons, we shouldn't teach non-scientific 'options' in a science class.  I whole-heartedly recommend teaching Intelligent Design or creationism (from all religions) in a sociology class, but it shouldn't be taught as an alternative to currently understood scientific theories.  See above for my explanation as to why these are not scientific.

You wrote: "Darwin didn't write the 'Origin of Life', he wrote 'The Origin of Species.'  To the extent that variations evolve from different kinds of animals, I believe this because it can be scientifically witnessed. (For example; dogs, cats, birds, bears, horses, etc.)"

You're correct on the first point and I'm glad to hear it on the second.  Darwin had almost nothing to say on the origin of life.  The biological theory of evolution deals exclusively with change in organisms over time AFTER life has begun.

You wrote: "Yet, the idea that life was came about by some random order of things, that molecules and atoms fell into place is highly improbable."

How improbable and how do you know this?  The problem with this statement is that we really how no idea how improbable the origin of life is.  As an analogy, consider the probability of being dealt a hand of cards with four aces and a king.  We can calculate exactly how likely that is because we can know everything there is to know about the deck of cards being used.  We don't have that information when it comes to the origin of life.  We don't know the exact conditions on the early Earth.  Expanding to the rest of the universe, we're only just now beginning to calculate how many planets there are out there in the galaxy.  Only then can we get an idea of how often life like ours might have developed elsewhere.  Thus, we can say very little about the 'probability' of life developing.  More about this can be found here: http://www.talkorigins.org/faqs/abioprob/abioprob.html

You wrote: "Couldn't the notion that there was a designer be concievable?"

Of course it is.  But it isn't scientific for the reasons given above.  

You wrote: "Darwin himself stated that to say the complexity of the human eye was by accident is non-sense."

This is probably the quote you're thinking of: "To suppose that the eye, with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree. (Darwin 1872)"

It's very common for creationists to quote this sentence and go on to convince people that even Darwin didn't think he was correct.  If you read the rest of the paragraph from which that sentence was taken you'll find this: "Yet reason tells me, that if numerous gradations from a perfect and complex eye to one very imperfect and simple, each grade being useful to its possessor, can be shown to exist; if further, the eye does vary ever so slightly, and the variations be inherited, which is certainly the case; and if any variation or modification in the organ be ever useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real. How a nerve comes to be sensitive to light, hardly concerns us more than how life itself first originated; but I may remark that several facts make me suspect that any sensitive nerve may be rendered sensitive to light, and likewise to those coarser vibrations of the air which produce sound. (Darwin 1872)"  He then goes on to describe possible scenarios that could explain the development of eyes like our own.  He even gives examples of organisms with the intermediates discussed.   

Such selective quoting is intellectually dishonest and referred to as "quote mining".  Numerous examples (including this one) can be found at http://www.talkorigins.org/faqs/quotes/ … ject.html.

Good luck getting an answer to your first question.  I know there are plausible scenarios out there.  In fact, I know there are many examples of colonial organisms available.  These are organisms that reproduce essentially on their own but work together as a group.  I could easily imagine that specialization of cells to increase the efficiency of food gathering might lead in the direction of true multicellularity.

Just to reiterate some points Kevin made (me beat me to the response):

The theory word theory several uses, and the scientific usage is nearly the opposite from the popular usage. The definition you mention is the one used by non-scientists, synonymous with the words idea, hunch or guess, and doesn’t really require any evidence at all. As scientists use the word (actually the first provided definition of the word in dictionary.com), it more closely is synonymous with principle or law. A theory is not a “baby law” that has any uncertainty or needs more evidence, it describes a broad set of data (instead of a law, which has a very narrow focus). So if there was a hierarchy, theory would actually be stronger than law. Since evolution is supported by thousands, or possibly even millions, of experiments across many disciplines (genetics, microbiology, biology, chemistry, geology, et.), it is considered to be firmly a theory, with no less degree of certainty than the theory of gravity (probably even more certainty, since we have a pretty firm grasp of the details of how it works).

Best,
Chris

With regards your first point, how can single celled life, reproducing asexually evolve into muticellular life.

The best scientific explanation behind the origins of life that I have read are described by Nick Lane http://www.nick-lane.net/ in his book Life Ascending. In it he details the conditions under which the first life probably evolved within 'hot smokers' found in deep sea trenches. It is the jump from this to the first single celled organisms which is currently being hotly discussed and experimentally tested.
The movement from single celled to multicellular life by comparison is a far less controversial topic. For instance although single celled organisms reproduce asexually, sex is not the originator of evolution, it allows recombination of genetic material so that new variations can occur, but it is genetic mutation which provides the raw material for natural selection to work on. Any cellular division occasionally produces mutations and so single celled life is perfectly capable of evolving (usually at a substantially faster rate than multicellular life).
Additionally most bacteria are capable of conjugation, a process whereby two bacterial cells can swap genetic material, this allows beneficial genes such as those conferring antibiotic resistance to spread rapidly.
As for the evolution of multicellularity, being multicellular can have several advantages, less able to be eaten by predators, greater control of movement, cell specialisation. And this process almost certainly started when a cell divided but remained clumped together, natural selection would then drive this forwards. In fact we have living species today that occupy every step from single celled life, simple multi-cellulars like sponges, simple body plans and cell specialisations like the hydra and more complex multicellulars like flatworms and finally ourselves and other animals.
Sex would have evolved after multicellularity, from conjugation, to simple gametes where there are no sexes, until a process called anisogamy drove the differentiation of gametes and finally the evolution of fixed sexes. Again there are many organisms alive today which show how this process would have developed.

The second point has been addressed by my colleagues, but I will say that the 'evolution is a theory' argument is tired and old. Despite the semantics, evolution is both a fact and a scientific theory, it is experimentally observable, verifiable and repeatable.
Darwin published his book over 150 years ago, and we have come a long way since then, it really doesnt matter that he couldn't answer questions about the origin of life. Modern biologists do not cling to his tenets, rather appreciate his contributions to mdoern science and recognise his work as of its time.

I just read this abstract in the Proceedings of the National Academy of Sciences USA and thought it to be relevant to this discussion.  A link to the paper is below.  I underlined the major points.

Experimental Evolution of Multicellularity

Multicellularity was one of the most significant innovations in the history of life, but its initial evolution remains poorly understood. Using experimental evolution, we show that key steps in this transition could have occurred quickly. We subjected the unicellular yeast Saccharomyces cerevisiae to an environment in which we expected multicellularity to be adaptive. We observed the rapid evolution of clustering genotypes that display a novel multicellular life history characterized by reproduction via multicellular propagules, a juvenile phase, and determinate growth. The multicellular clusters are uniclonal, minimizing within-cluster genetic conflicts of interest. Simple among-cell division of labor rapidly evolved. Early multicellular strains were composed of physiologically similar cells, but these subsequently evolved higher rates of programmed cell death (apoptosis), an adaptation that increases propagule production. These results show that key aspects of multicellular complexity, a subject of central importance to biology, can readily evolve from unicellular eukaryotes.

http://www.pnas.org/content/early/2012/ … tract?etoc