why is belief in reincarnation a serious problem?
It might be different between a Catholic and a Protestant, but here goes:
The Sadducees and Pharisees were at odds on the resurrection of the dead. Jesus said the Bible shows that God "IS" Lord of Abraham, Isaac, and Jacob.
Scripture gives clear indication of things and is explicit in others and it is a 'serious' error to ignore clear teachings of scripture. Hebrews 9:27
Just as people are destined to die once, and after that to face judgment.
And here is where it gets Salvific and why:
Hebrews 9:28 so Christ, having been offered once to bear the sins of many, will appear a second time, not to deal with sin but to save those who are eagerly waiting for him.
"Once" is essential to the passage and incredibly emphatic concerning Christ so must be emphatic concerning man by virtue of the essential comparison. Hebrews makes it more emphatic that it has to be only once, when it describes Him 'coming' a second time, "not to deal with sin." That is why Hebrews 4:6 is so emphatic about the anathema of any other sacrificial system, save Christ alone (only/once).
Question: "Can I believe in reincarnation, without doing damage to this clear scripture presentation and more importantly, the presentation of saving grace?"
A person can make mistakes and still be within the trusting Grace of God. "Can" is always something, somebody wants to investigate for themselves, when they diverge, especially on potentially salvific matters.
Respectfully,
-Lon