But in your hearts set apart Christ as Lord. Always be prepared to give an answer to everyone who asks you to give the reason for the hope that you have. But do this with gentleness and respect, keeping a clear conscience, so that those who speak maliciously against your good behavior in Christ may be ashamed of their slander. 1 Peter 3:15-16

Peter tells us that being calm, gentle, respectful and kind are always the best approaches. Getting angry only gives the accuser more reason to distrust your God. By being happy and relaxed, you put the listener at ease and their defenses drop.

Another good approach is to just be yourself. Religion scares people because it feels high, holy and unattainable for those that sense their own imperfection. By showing someone that you can believe in God and be normal, transparent and vulernable says a lot.