As normally cited, karma refers to the principle that “what goes around comes around.” It’s spiritualized in Eastern religions, of course, with the good karma, bad carma, having some interesting effects.
Stepping back, we can see where the concept came from. It came from simple observation. Just as surely and frequently as time heals all wounds, time wounds all heels. So incorporating that into spiritual beliefs is not at all inappropriate, because it appears as an ubiquitous principle.
Christianity goes Eastern religions one better (in my view) on this one. Christianity, through St. Paul, told us that we reap what we sow, a statement that is parallel to the general statements about karma. But St. Paul made it clear that he was not talking about some impersonal force or principal. He gave a reason for it: God will not be mocked.
Blessings,
Gerry
