During my deconversion process, I had given up the idea that the Bible was without error. There was contradictions, not just within the text itself, but within the content, as well. Claiming the Bible was inerrant, became increasingly difficult for me to accept. I came to the decision that God did not pass along a perfect document, but maybe there was still truth that you can get from it. The Bible seemed more like it was a collection of various thoughts and interactions with God. And, if that was true, than I could still get something from it. I had given up any beliefs of a young Earth, a true Adam and Eve, the Biblical story about the Earth's origins, Noah's Flood ...etc. I had given up quite a lot. All these things had an enormous amount of evidence to demonstrate that the Bible was inaccurate. But, the one thing I had clung to was the argument of the Prime Mover. God must exist because there would be no other way for the universe or life to come into existence on it's own. It was around this time that I began to discover the logical fallacies.
If you look up the logical fallacies online there are giant lists of them. In practice, there seems to be only a handful that are used over and over again. The most common ones are: Argument from Ignorance, Argument, from Antiquity, Straw man Fallacy, Ad Hominem, Post Hoc Ergo Propter Hoc, Appeal to Authority, Appeal to Complexity, Appeal to Popularity, Appeal to Emotion, No True Scotsman, and the Slippery Slope Argument. These are the logical fallacies that I run into, pretty much, on the daily basis.
Logical fallacies can only be fallacies when they point to a flaw in reasoning. There may be some cases when an argument may seem like a fallacy, but is not actually flawed reasoning. For example, an appeal to popularity, doesn't demonstrate something is true or valid, but appealing to popularity maybe valid if you are only interested in what is common to that group. Christianity is the most common religion in America, so I am more likely to run into a Christian in American than not. I am not claiming that Christianity is true, only that it's popular in America.
The flaw in my reasoning about the origins of the universe and life is that I was making an Argument from Ignorance. Another way to state my argument above is, "We don't know or understand how the universe or life began, therefore it must have been a God." The first half the statement is in contradiction to the second half. By claiming ignorance, it is then illogical to claim to know how these origins began.
I find the Argument from Ignorance used most often when a theist is claiming that science can't explain something, and therefore it's acceptable to believe that their belief is true. Each truth claim must be supported by it's own evidence. The lack of evidence for one truth claim doesn't then validate another. If someone has a belief that some God-like entity is responsible for some event, the existence of this entity would first have to be demonstrated, and then they would also have to provide evidence that this entity is capable of doing the things that they are claiming it has done. Without the evidence, the claim is unreasonable to accept. Simply saying. "You don't have an answer, so my answer is true" is flawed reasoning. And, that is the Argument from Ignorance fallacy.