Does it make me any less of an Atheist if I answer a question about Christianity?

I was a Catholic and a Christian for 37 years of my life, 27 of them voluntary. I learned a lot in those 27 years, and just because I no longer believe in their God, I still have that knowledge. So why should Christians feel I am putting them done or picking on them when I answer a question about a matter of faith, when I can provide a knowledgeable answer? It isn't fair to judge the correctness of the answer just because I am now an Atheist.