The idea of convincing them they’re agnostic is really ingenious for a number of reasons!
First, it is so easy since atheists main motivation for absolutely denying the existence of God is pride—the pride of being “awakened” to the “truth” when everybody else is mindlessly following God. This perceived intellectual superiority solidifies their faith of non belief. Yet when you simply explain why an agnostic is much more intellectually superior, since they practice very little faith at all, only relying on that which can be observed, then they will likely gradually lean towards weak atheism, and then agnosticism (moving towards theism) out of sheer need to feel intellectually superior to others (in this case, both atheists and theists.)
From this position of agnosticism, one can get the person to claim theism is possible, albeit unknowable. Simply admitting that theism is possibly correct is a huge step in helping them have faith in God.
Ultimately, this is the best tool to get them to admit the possibility that theism is correct. Thank you for sharing this!
You gotta walk before you run, and you’d be amazed at how many have found Christ by first admitting that, ultimately, they don’t really know if there’s a God.
Admitting a God is possible is the first step, and the very first thing it does is convince all onlookers of the intellectual dishonesty of the secular humanist (which is really what an atheist is).
As such, it is so much easier to prove there are no such thing as atheists than it is to prove there is no such thing as God.