Do you think the number of atheists in the world will increase after this pandemic? And what will be the biggest reason for their conversion?
Unfortunately the reverse is likely to be true as morons turn to god begging to be spared and of course when they don't die, as the majority will not, they will give thanks to the big sky daddy and pledge their lives to it in gratitude.
It is a sad fact but the majority of people are sad, superstitious idiots.
I think that the number of nonreligious persons will increase slightly - maybe by 2% or so.
What they will call themselves, though, (atheist, agnostic, nonreligious, etc.) is uncertain. The biggest reason for conversion, initially, will probably be a loss of trust in institutions.
But, this is just a guess. I am neither a sociologist nor an economist.