“One thing I do know, that though I was blind, now I see.” They said to him, “What did he do to you? How did he open your eyes?” He answered them, “I have told you already, and you would not listen. Why do you want to hear it again? Do you also want to become his disciples?”
You don’t have to know everything to follow Jesus. People will come to you and say “oh, you’re a Christian??? Well, how do you explain…” and they’ll try to tell you something they learned on You Tube. Don’t let it bother you. You’re response can be as simple as the man who was blind… “I’m not sure about all that, but one thing I know, Jesus saved me.”
Sure, go back and find out what the argument against Christianity actually is, and find the answer (don’t worry, there’s always an answer), but you don’t have to know the answer in the moment. When someone is asking and asking and asking, you ask them… “why are you asking? If I find the answer, will you follow Jesus too?”
They’ll usually leave you alone at that point… or they might be honest and say “I’ll never become a Christian.” Then you can simply say “then why are you even asking questions, if you simply believe what you believe regardless of the evidence?” It’s the atheist who usually thinks he’s being rational, when you point out they’re not, it tends to irritate them.