"There is a god because e = mc²"

[MTL]

An apologist friend of mine said this a while back and I thought I'd pose the question here. He says, there is a god, because e=mc².

Any clue what he could be talking about? Or where he could have gotten this idea?

I wish I could say I was adept at mathematics and physics, but I am not.

But I recall someone of my acquaintance, who is both very scientific but also a theist,
observing that the second law of thermodynamics dictates something to the effect that
entropy succeeds over time; everything winds down, like a clock, including the Universe

...and that raises the interesting question about who wound the clock up, in the first place...

But I'm way out of my depth with it, sadly.