It has occurred to me that were to get substantial evidence we lived in a infinitely large and old multiverse, the effects on religions would be massive.
A incredibly large number of religions are based on the idea of a deity or deities creating everything that exists. However while our universe would still be finite the newly discovered multiverse never even had a beginning in this scenario.
The evidence for the newly discovered multiverse is substantial, denying it would be like denying relativity. We can directly observe other universes with new technology, though we can't see anything above the atomic level, however this is still sufficient to figure out how their physical laws differ. Scientists haven't found any universes that are hypothesized to be very similar to to our own, but they can prove that while choosing which new universes to look at is random, the multiverse is infinite and had no beginning as thus universes just like our own are almost certainly infinite in number.
Should in real-life we discover evidence that suggests a infinite multiverse it is unlikely the evidence will be quite this damning. This scenario is designed to make it clear, that in this scenario the people who deny the evidence for this multiverse are like solipsists in that they would have to deny the ability to trust their senses and thus other equivalent claims like the fact objects fall.
What would be the effect of this evidence?: Both initially in the first few months when the evidence wasn't undeniable, and after a year or more once the evidence can't be plausibly refuted. I would like answers both for what it would mean to religious individuals, and how religious organizations would react as time progressed, the long term effects on religion will be highly speculative, so I encourage most of the detail to be on the effects in the first few decades.
The technology itself is irrelevant and is assumed to be of very little actual use. This question is primarily concerned with the reactions religions might have to evidence that undermines one of their most vital tenets, though certain religions wouldn't be affected very much, because existence being eternal and infinite wouldn't run counter to them necessarily. I also don't see a lot of religions liking the idea of redefining their god to be finite and for admitting humans are infinitely insignificant cosmically.
I don't exactly see this as being a death-blow to religion, with it only affecting some religions and potentially drawing people to other religions both old, and to some of the religious sects that would be produced by this.
And of course one only need look at the number of creationists to see how well religion can deny that which is utterly undeniable, the fact evidence in this situation is even more damning than that for evolution, likely won't make a whole lot of difference to some religious groups.
Edit: The fact the multiverse is infinite and eternal wasn't postulated, it was confirmed by direct observations, I'm not sure what those observations would have to be but that is irrelevant, what's important is that you couldn't just look at the evidence another way, to deny it being eternal and infinite means rejecting the evidence altogether.
Edit 2: Well I understand that some people have problems with whether observations that could prove the assumptions in the question may be impossible. But even if they are impossible, in the scenario they just turn out to be how the universe is even if it doesn't necessarily make sense.