theists: what kind of evidence would falsify god?

For there to be evidence to falsify god...there must also be proof that god exists or ever did exist...so your question is kinda a mute point.

You can't falsify the statement "there's a goblin on my shoulder", because goblins don't exist. your statement was already false...

No evidence would falsify God - as the vast amount of evidence rubbishing the Bible's claims, todate, has been rejected by most Christian apologists.

Theists base their understanding of God on faith, not science or evidence. This is possibly be a big part of the problem here.

I suppose if I could hear moral relativism/subjectivism argued effectively.

Of course that would not be "evidence" by it's strictest definition. All forms of moral ideology are argued philosophically, not evidenced through physical examination.

nothing there cant be evidence to disprove God because he is undenyable

God is an ultimate explanation and unfalsifiable.