In your opinion what causes christians to believe in Jesus

[John 6IX Breezy]

And why do you separate out the act of creating Earth from the rest?

Because the text separates them, is that not a simple answer? The first day starts in verse three and is kicked off by the creation of light, that's it. Every child in Sunday school knows this, Day 1 = God makes light.

The first two verses give the lead up to Day 1. We have a universe already created and an earth in a shapeless empty form. No mention of how much time elapsed or by what means any of it came about.