Karma is intentional actions with moral consequences. All actions have physical consequences, because the law of causality states that every effect has a cause and every cause has an effect.
Something similar operates in the moral realm. It is called the law of karma: what goes around comes around; what a person sows, so will they reap. Reincarnation says that if you do not reap it in this life, you will reap it in another. You do not get away with anything.
Now it is important to understand that we are not punished for our sins; we are punished by them. We plant the seed and reap the result. Justice is built into the structure of the cosmos. There is no need for a future judgment in some celestial afterlife.
Moral consequences for our moral actions are the only way we will learn to be morally responsible. The point is not to punish us, but to reform us. It is an educational system built into the very fabric of the universe, and the lessons will be repeated until they are learned.
