Well then a huge amount of Christians went straight to hell after death because many waited to be on their death bed to be baptized so all their sins would be forgiven.No, they didn't believe that we would stop sinning after we are saved. That teaching is directly contradicted by a large amount of Paul's teaching.
As for the people who lived from Adam to Pentecost, they were under the OT, and subject to a different set of commands. When the perfect came, the imperfect was eliminated. As Jesus said, not one jot or tittle will be done away with until all is accomplished. Then on the cross He said, "It is finished." He had fulfilled the Law, and so it was canceled in favor of the NT. No, none of the people in Abraham's Bossom were immersed, because that was not a commandment during the OT, but it is in the NT.
Baptism was for the forgiveness of sin.
You could check this out....no need to trust me.