- Avoid using scripts
2. Avoid talking about the theory of evolution, abiogenesis, or Big Bang cosmology when the discussion is about the existence of God
Personally, when I get into a debate with a Christian over the existence of their God and the Christian starts talking about evolution, abiogenesis, or Big Bang cosmology, I immediately concede the point. More specifically, I grant to them, for the sake of argument, that evolution, abiogenesis, and Big Bang cosmology are all incorrect. Mind you, these are interesting topics for debating, however all are irrelevant to the question of God's existence. If evolution was proven wrong tomorrow, that in no way proves that a God exists. Christians have the "burden of proof" meaning they are the ones making a claim that we atheists lack a belief in. It is up to the Christians to provide the necessary standards of evidence to prove that their God exists. There is no dichotomy between the Big Bang and God started the universe with the wave of his hand. There are many other theories than just these two. If you want to follow scientific principles and prove that the God of the Bible exists, then you have to provide positive evidence for your claims and not rely on disproving other theories.
3. Ask questions
Christians have a much harder time with this one than atheists. Atheists have natural questions we must ask Christians during every debate because there as many denominations as interpretations of the Bible. Atheists have to develop some sense of the God you are talking about and what you personally believe. I find that Christians do not extend this action to atheists. As long as you're excluding the lack of a belief in a god or gods, the Christian doesn't know anything about what the atheist believes in or the reasons for this said lack of belief. Avoid lumping people together and committing the fallacy of a sweeping generalization. In addition to these types of personal questions, always feel free to ask for clarification of a response. This will never hurt the conversation and can only help. Plus, you two may agree on the issue but a small semantic difference is holding up the conversation.
4. Throw Bible verses around as if they carry weight
Imagine yourself in a debate with a Muslim and that person gives you a verse from the Qur'an in order to prove a point in a discussion that doesn't have to with Islamic teachings or anything of that sort. The verse means nothing to you because you believe that the book is not divinely inspired and is a bunch of hogwash. Guess what? This is how atheists view your holy book! In order to use the Bible as any type of evidence, you must first give a compelling case on how you know that the Bible is the word of God and isn't a make believe fairytale like every other religious text out there.
5. Substituting "I don't know" with "God must have something to do with it!"
This is called the "God of the gaps" fallacy. I will have a post on this concept eventually, but, essentially, the fallacy is made when a theist offers their god or gods as an answer when us humans do not currently possess one. For example, when a "medical miracle" happens and we don't know why, some people turn to God and this is a fallacy from ignorance. Just because you can't possibly think of anything other than "God did it!", does not mean that is the correct answer. In this case and in debates in general, the honest response to say is "I don't know". There is nothing shameful about this response in the slightest. Science says "I don't know" all of the time, but at no point is it justified in giving any answer it wants (such as a God). Saying "I don't know" during a debate and not attributing events to your God is honest and will ultimately help the conversation.
If you have any other suggestions for tactics Christians should avoid when debating atheists please comment below! Have a wonderful day!