I run into this argument constantly online. Because God is unfalsifiable, it’s senseless to believe in him. Many Christian apologists argue against this, saying there are certain facets of our religion that you can validate historically, archeologically, etc. But I’m more lenient than that. Let’s just say that God is unfalsifiable.
If God is unfalsifiable, there is at least on possible world where God exists. If this number was zero, the concept of God would be falsifiable. Or even falsified.
So from there, let’s look at Pascal’s Wager. Basically, you don’t know if God exists. There is a non-zero chance of an infinite reward or of infinite punishment. Heaven or hell.
So because the chances are not zero, Pascal’s Wager tells us that we must explore the possibility of God. Whether it is to get into heaven or stay out of hell. The fact that God is unfalsifiable paired with the wager mean that the concept of God is one that must be explored further.
So while the atheist’s strange non-position as a ‘lack of belief’ may shift the burden of proof to the theist, this argument should help show the atheist that the argument is for their benefit, not yours. And once they realize that you are on the same team, they may be more open to hearing the truth.