QUESTION: As far as I know, you don't have to be Mormon in this life to get to the celestial kingdom, correct? What benefits exactly go to Mormons in the afterlife, when compared to someone else.
We have just gotten a head start.
If a Mormon leaves the faith, is this in itself considered a serious sin?
Pretty much, given that they are denying something that is true.
Unless I'm mistaken, God was once a human like us according to Mormons, correct?
It's sort of implied, but it isn't quite doctrine as far as I recall.
If so, how do we know everything he does is perfect?
Whatever or whoever God was, what He is now is what matters.
And an individual question: Were you born Mormon, or did you convert?
I was born into the Church.
If you were born into it, have you ever doubted it? (Not talking about a passing doubt, talking about a time when you seriously considered whether your faith was true.)
Without going into too much detail, there have been moments in which I had questions with major implications regarding whether the Church is true.