It's useful to ask the question outside the realm of theology. We accept many things on the basis of trust: for example, the fact that a hydrogen atom has one proton and one electron, or the fact that Britain is an island, or the fact that vaccines confer immunity. We believe these things primarily because there is no reason to doubt the veracity of the claim, and we have confidence that the claim could be proved, or has been proved, even though we haven't seen the proof and might not understand it. But if there is reason to doubt the claim, for example because we don't trust the person making the claim, or because other people claim the opposite, then it's reasonable to argue that we shouldn't believe the claim unless the person making the claim can prove it to our satisfaction: at that point, the burden of proof falls on them.

It's useful to ask the question outside the realm of theology. We accept many things on the basis of trust: for example, the fact that a hydrogen atom has one proton and one electron, or the fact that Britain is an island, or the fact that vaccines confer immunity. We believe these things primarily because there is no reason to doubt the veracity of the claim, and we have confidence that the claim could be proved, or has been proved, even though we haven't seen the proof and might not understand it. 

But if there is reason to doubt the claim, for example, because we don't trust the person making the claim, or because other people claim the opposite, then it's reasonable to argue that we shouldn't believe the claim unless the person making the claim can prove it to our satisfaction: at that point, the burden of proof falls on them.