If Darwinism is true, then there is no purpose or meaning to life, there is no morality, there's no qualitative difference between humans and animals, there's no life after death, and there's no purpose to human history. Now, are you trying to tell me that it doesn't really matter if people believe we evolved or not?

Why so many mentions regarding Jesus from such a wide variety of sources (Pliny, Tacitus, Lucian, Josephus, to name a few)? Because Jesus of Nazareth was a man of history, who made a profound impact on history. There's no good reason to doubt that Jesus existed, or to think the real Jesus was completely different from the one depicted in the Story.

Every worldview has its ambiguities - debatable elements that people simply will not see to eye on. There's nothing wrong with that as long as the disagreement is principled and dignified. I actually think that arguments - as opposed to quarrels - are good things because they're the best way to figure out what's true. Share your reasons, listen carefully to each other, be nice, and may the best idea win.

People are tempted to think (understandably) that if God were really good He'd never allow any evil in the world at all. But I don't think a perfectly good God would never permit any evil, and neither would others, I wager, if they thought about it. Rather, I think that a good God always prevents suffering and evil unless He has a good reason to allow it. That's the crux.

If man is not special, if he's not deeply different from any other thing, then there's no good reason not to treat him just like any other thing when it's convenient for us to do so.

If the unborn is a human person, no justification for abortion is adequate.

Always make it a goal to keep your conversations cordial. Sometimes that will not be possible. If a principled, charitable expression of your ideas makes someone mad, there’s little you can do about it. Jesus’ teaching made some people furious. Just make sure it’s your ideas that offend and not you, that your beliefs cause the dispute and not your behavior.