To stand before God and say, "It all seemed to stupid" or even "I was a good and moral person" is not enough to avoid eternal punishment.
How do you know? Sounds like reasonable guy. What happens to people in the middle of nowhere in some tribe that has never even heard of God or Jesus or babies that die not knowing god? They burn in hell because nobody bothered to go tell them about this crap? If there was a god I think religions would be a pretty big insult to his intelligence. Shame you can't see this.
The Bible says that there is only "one way to the Father through Jesus Christ" and "every knee will bow and confess that Jesus Christ is Lord," "all have sinned and fallen short" and "Whosoever believes in Him will have eternal life." I did not write the Bible. I just read what it says and follow it to the very best of my ability, this is how I "know."
As for babies, tribesmen etc, I believe that the Catholic idea of "Purgatory" is not too far off, although there is not necessarily any evidence of being able to pray for the souls there, but the English translation of the Bible has done a disservice of simplifying "Sheol" and "The Grave" into "Hell." In a nutshell, God is fair. He puts fairness into our hearts. Jesus took the "keys of Hades" during the three days before his resurrection and during that time may have very well spoken to the souls that are there in what may be a timeless place and gave them the fair chance to accept or deny Him. This is my belief. Granted, many Christian churches do not preach this. They have more of a "black and white" view, but I don't think that is necessarily correct and even the Bible supports my viewpoint and I agree that it would not be fair to send someone to eternal damnation without giving them a fair chance.