I have a hypothesis that for any definition of God with real-world implications, there exists compelling evidence against that God's existence.
If, on the other hand, God's existence has no effect in the real world, then God is a purely mental construct, i.e. imaginary.
The fact that atheists supposedly cannot prove God's nonexistence is often used as an argument against active atheism. However, active atheism is not about trying to convince people that God exists, but rather that people who claim that God exists and that therefore some action is required from us have no basis for these claims.
In other words: while it might be true that atheists can't disprove God, it is also true that theists have absolutely no basis for claiming that anyone should feel compelled to act in a certain way because of God. Atheists are therefore justified in strongly criticizing such claims, and the people who make them.
Every religion has its own definition of God; these definitions often contradict each other on key points (e.g. omniscience, omnipotence, "living", "personal"), and yet they all act as if they are talking about the same thing when they use the word "God".
It's impossible to have a meaningful discussion about something about which there is neither physical evidence nor even an agreed definition.