How does "karma" work when every thing is destined at the time of birth?

REALLY?

Everything is destined at birth. But, that is our Karma for the present birth.

What we are and will be doing in this life is writing our future Karma, based on the power of free-will that has been given to us.

We can be good boys or bad boys; the choice left to us entirely.

Some people say "I gave him a good whacking; he had it coming; how can he be so mean? he needed to be taught a lesson."

Who are we to teach anyone anything? If we are happy that a bad person is suffering that only means that we are yet to get there. All the suffering that we experience in this life is like a yagna (holy fire), where our thoughts and actions get refined so we become better humans every passing moment.

On the other hand, there are a bunch of us, who will do whatever we want to do just because we can do; nobody to question us.

Otherwise, how can we explain kidnapping children, steal their body parts and sell it to high paying donors; loot and rape at will in a civil war; drive an automobile into a group of fellow humans; bomb a civilian population consisting of women, children and elderly; fleece the unsuspecting patients at the hospital; slice people’s necks in the name of God; conduct underground and under sea nuclear tests killing millions of organisms, insects and animals; the level to which humans can stoop is endless, isn’t it?

Can we humans, even for a moment, be foolish to think nature is going to ignore all this and keep silent? You see, whether we accept or not, the cosmos is one intelligent being, watching our every action and giving it back in time; we are under-estimating the intelligence of the Universe.

As in the judicial system, ignorance of the law is no excuse.

But, there is always a gap in time (sometimes even across lives) between our actions and the result.

An example would be similar to this. we take a loan from a friend. The friend forgets all about it. But, we remember it. Years roll by and at his daughter’s marriage, we give him back the loan amount with interest as a wedding present.

That is what Karma does for us. Delayed justice. But justice always.

Life is complicated till we understand this. But, once we have understood this, it is up to us to keep a check on our passions and lead the straight path.

It is difficult, but since we have the key to the question of life, we can always correct ourselves when we find that we are deviating.