Don't confuse the messenger for the message. I'm not even Christian, let alone a fundamental one. You asked how the God of Numbers could be reconciled to the teachings of Chirst. I attempted to do so. If you don't agree with my view on it then that's very well. I never I said I know all the answers. All I attempt is a counter to there being no way to reconcile it.
For what it's worth, I don't believe that Heaven and Hell are literal. I do believe in the afterlife, but I don't believe that either Heaven or Hell affects that afterlife, at least, certainly no more than either concept affects this life. Christ said, "The Kingdom of Heaven is at hand," not "The kingdom of Heaven is waiting for you after you die." As for Hell, there are plenty of people living in their own Hell as we speak. My point is both are metaphorical states of mind. Is that all they are? Perhaps not, but certainly they are at least that much.
Yes, you are right, Christ never taught us about Grace. But then, how could he? Before he died and was resurrected there was no Grace, at least not in the sense that we realize it as today. So what Christ taught us was how to live by the Law and to be Holy and righteous unto God by the Law.
So in essence, (and I'm sure that saying this will get me some criticism, but so be it,) what Christ taught us was something that only he could do. This is why I do not call myself Christian, because Christians attempt to live their lives by Christ's teachings, to do as he did, to live as he lived. (My apologies to all those who would say that I am generalizing Christians. But, let's face it, most if not all Christians claim to try to live by Christ's teachings.) But I know I cannot do these things, I cannot live by the Law. The Bible also says that if you break one law you break every law. Well, everyone breaks at least one, which means everyone breaks every law. Sorry but I won't live my life dedicated to a Law that I break constantly. That is not for me. If it is for you then I encourage you to keep the whole Law. And may God help you with it.
As for how many and which people are God's children I cannot answer you. God chooses who his children are, not me. Do I believe that everyone is God's child? No, sorry, but I don't. Do I believe that someone has to believe what I believe to be God's child? Absolutely not. My parentage does not rely on my beliefs. I could believe that I was born of a hippo from the planet Neptune, but that wouldn't change who my earthly father was. Nor would it change my Heavenly.