Removing or moving the index file whilst retaining current URL links

Hi guys

I use WP as a cms and want to replace the first page (index.php) with a static page which i’ll also be calling index.php

I find that if I move or replace the index.php it breaks my whole site so I’m assuming whatever is in index.php is beig called when the other posts and pages load.

Is there a way to replace the WP index.php with my own whilst maintaining the integrity of the rest of my sites structure?

Many thanks in advance.

Mark