I hear ya on the walking away. I was like you... when the church doors were open, we were there. I left the fellowship not because of faith, but, because of other reasons.
To answer your question, why Christianity? Because of one verse... plain and simple. 1 Corinthians 13:13. "Now abide, faith, hope and love... but, the greatest of these, is love"
To me, Christianity, or any other "religion", should be based on love, and love alone. It's so easy to have a loving nature towards society, IF you allow yourself to. Sadly enough, I feel that most people find it easier to be sour pusses towards society.
Bottom line... love conquers all, and it truly does.