Nothing you do matters. At at all. To anyone. And it never will.
You can have a hundred children or kill a hundred children and it will be forgotten in time. Time is long. Think you're special because you can trace your family history back five centuries? That is nothing. Don't think in centuries, think in thousands of centuries. Think in millions of years. A hundred million years? Less than an instant.
Nothing made by people matters. Fiction -- which includes religion -- visual art, music. Meaningless, all of it. Architecture crumbles overnight, relatively speaking. Even our affect on the environment will be erased just a few centuries after our species has died off (an inevitable event, by the way).
Our lives are pointless.