Unfortunately, the Theory of Evolution through Natural Selection is still a relatively controversial and touchy topic for many people.  While it is no longer debated in the scientific community at large, the average person often misunderstands various parts or will argue against evolution because the media makes a big deal out of the dissenters and the ongoing debate.  It may never be possible to make all of the anti-evolution crowd see how evolution is a fact, it is possible to spread knowledge and a greater understanding by knowing how to debate on the side of pro-evolution.

The most important thing to remember when starting a debate or responding to comments that could lead to a debate is to be respectful of your debating opponent and stay civil in tone of voice and conversation.  This may be difficult for many people because defending a belief that you strongly believe in and know is fact against someone who is less informed and maybe even a little bit stubborn is very frustrating.  However, don't lose your cool and resort to personal attacks or offensive body language such as rolling your eyes or sighing loudly (of course if you are debating non-verbally over the internet or in writing, feel free to make whatever noises and gestures you would like!).  Stick to the facts and you will win the debate or at least come out on top even if you do not change the mind of your opponent right away.

Argument Against Evolution: "Life starting by inorganic molecules coming together to form organic molecules is statistically nearly impossible."

How to Debate the Argument:  This argument could be brought up in several different ways, but they all take aim at how life started on Earth.

 This sort of argument usually comes from a Creationist who believes in a God or at least some sort of higher power that put humans (or at least a primitive form of life) on Earth.  Many times they will skip the word "nearly" in this argument and if that is the case then the argument becomes that nothing is ever completely impossible.  Yes, there may be such a slight chance of something happening that it seems unlikely, but nothing is completely statistically impossible.  To circumvent that debate, most skilled or knowledgeable debaters will put in a "nearly impossible" instead and then this counterargument is now invalid.

This is still not a problem because there are other fallacies in this statement that are just as easy to blow wide open.  You could start out by informing your debate opponent that the Theory of Evolution through Natural Selection, as proposed by Charles Darwin, does not try to explain the origin of life on Earth.  The formation of the first life is not encompassed by the Theory of Evolution and therefore cannot be used as an argument against it.  However, this is not the only way to win this debate.

The next argument you can use to debate this point is knowing about the various ideas that are accepted right now about how life did first come to be on Earth.  Many believe life started in or near the hydrothermal vents in the bottom of the ocean.  There are currently many primitive life forms that live there that could indicate these areas have the right conditions to form life.  Others believe in the idea that life and the first cells came to Earth on meteors that were commonly striking the Earth before it had a thick atmosphere to protect it from these types of impacts.  You can also point out that scientists were able to easily create organic molecules in the lab using a simulation that was similar to the early years of the Earth (although their exact components have since been proven to not be correct, so using this argument may lead to an attempt to discredit the rest of your argument).

The bottom line is that evolution is the accumulations of adaptations over time that create new species.  Using an argument about how that life first started is not an argument against this definition and may be the correct way to win this debate.