The overlap is easy to spot. They are both faith based groups. Faith is believing something in lieu of evidence.
Which is part of the reason why the Q crowd doesn't always mesh well here. Evidence is usually requisite at this .win. "Trust" in a plan is hard to come by.
This is not how Christians define faith. Faith is the certainty of things hoped for, a conviction about things unseen. Things unseen and hoped for can have evidentiary support for their existence and manifestation.
But Q is an oddity that borders on idolatry for some, which is why the dovetail, per your OP, seems odd. The two faith concepts are mutually exclusive.
Curious... If faith based groups don't fit here well, then you must not get along with the scientists and atheists either, right?
The dictionary is usually the authority on defining words:
And even your definition fits his simple definition if you boil it down to what it is. Your certainty of a thing unseen (cannot be proven) is saying the same thing basically as he was. We cannot see god (prove existence) or else no faith would be required if he was here in front of us. Faith spirituality belief none of those can be seen, roven or quantified in any way but doesn't stop them from existing.
I see what you are trying to do here and it doesn't work with scientists at all and you lose credibility with this argument IMO. Here's why:
Atheists: YES! This comparison works for your point. Atheists absolute BELIEF there is no god is a faith of its own and cannot be proven.
Scientists: Nope. Comparison does not work. Science uses the scientific method and it by definition ever changing and evolving as new things are discovered and old thinking disproven.
Had I not felt like they were being disingenuous and baiting with that last question, your comment is how I would have replied.