The death of Jesus wiped away all sins, correct? Past, present and future? If so, then you could become a Christian, still sin, die, and still get into Heaven.
The concept of Christianity is absurd and vile. You do terrible things, someone else gets punished for them, and you get the reward of their righteousness.
People say god has perfect justice and perfect mercy. That's a contradiction. Justice is giving someone the punishment they deserve. Mercy is not giving them the punishment they deserve. If you have one, you don't have the other.