It took me a few years to realize that admitting ignorance is not the same as admitting that you are wrong. Your faith, your beliefs, your system of living are not automatically called into question when you get stumped. When I was younger, a friend asked me what I thought about a complicated social/religious issue. I didn't have an answer, so I broke down crying.
I didn't cry to manipulate him -- I cried because I had no idea and it had never occurred to me that it was okay to simply say "I don't know." I cried because of the frustration of trying to come up with the perfect answer when I didn't have the remotest clue what to say. I cried because, let's face it, the internet has trained us to always come back with an answer no matter how dumb it is or else we "lose" the argument.
Folks, no one has all the answers. No matter your background or personal beliefs, you're going to come across people who disagree with you and who want you to explain things that you maybe have an opinion on but don't know much about.
Let's revisit the scenario with my friend. After 10+ years, all I've come up with is "I don't know. Plenty of people have theories, but I can't give you the detailed explanation you're asking for. I simply have to trust that God is leading me right."
And that's it. Is it satisfying? Not really. I'd like to have all the answers, but I don't, and I've come to terms with that.