You don't have to explain it. And, really, in order to explain it you would need a character within the world who figures it out.

You can, if you want, hint at it though. The way you tell the story will give the reader the idea that maybe these things aren't magic but merely coincidence or wishful thinking.

I wrote a book last year where most of the people believe in the gods, but there is no magic, no instance of divine intervention. There is some centuries old and highly advanced tech that only a few understand. (Most of the societies no longer use electricity for anything because they believe it was "the Spark" that gave Machine sentience. Which turns out not to be what happened, but there's a disconnect between the available knowledge and the actual history - some of it deliberately muddied by certain factions within the world.)