.........the beginning was the universe, infinite but yet to be created as we know it. How can something not yet created be infinite? Imagine a box with a tiny dot inside. Something like this.

................wait - in one corner of the box is a tiny speck.  In the moments after the Big Bang all the particles of the known universe rush away from each other.  The tiny speck is consumed and the box is filled.  Now the infinite universe is outside the box and racing away into eternity.

The speck is caught inside and trapped forever -  a lost part of the infinite universe, and who can know what lies beneath ....

This dot is waiting for the Big Bang so it can expand into something we will recognise just as soon as we actually exist.  When it does, it will fill the whole box and become the universe that we know - all the rest is infinite.