Yes this religion @Shawn_Murphy describes is fundamentally one of self-perfection requiring multiple lives to achieve it. This is Hinduism (aka Hari Krishna) not Christianity. I don’t blame people for looking to such alternatives considering how so much of Xtianity, which under an obscuring rhetoric transforms grace into an indulgence style purchase of salvation by believing the “correct” things.
But there is much more to Christianity than such distortions. Perfection in the sense of removing all sin is indeed a requirement of heaven – there is no doubt about that. We just know that this is not something we can do for ourselves no matter how many years or lives we have to do it. Sin doesn’t just go away – quite the opposite, it grows like a degenerative illness. And that is not the purpose of the physical life anyway – how could it be since as you observed that is exactly where sin starts and comes from. Neither is grace an escape from the consequence of our choices and actions, but has to do with the fact that the consequences depend greatly on how you deal with them.
Another big difference is that we know this is not some ideal system – not the way things were supposed to be. This is about fixing something which is broken. Hinduism on the contrary seems to be trying to make life into some ideal system where we can reach perfection eventually by trying over and over again. We see no hope in that at all and see more hope in resurrection as a restoration of way things were meant to be – a relationship with God without sin. The big question is how can this come about, because if this is envisioned as some instantaneous transformation by divine magic then I cannot believe in that any more than Shawn. The death of Christ on the cross and the call to take up the cross and follow Him, should point out that this is not something we should expect to be so easy. But we do need to be willing and thus a choice of some kind is required.