I do not understand your thinking. Yes, you are right to criticize those who misuse science to “prove” the existence of God, but to say that because they are mistaken that existence of God is less sure is also clearly false.
God is true because God is real. If the multiverse is true, then it must be real also, but we have a long way to go before we can say this. Nothing in the information you quote says that the multiverse is true or real, only that it maybe within the realm of possibility.
Again the evidence indicates that the universe had a beginning, t = 0, which means that time and space along with matter and energy had a Beginning. Beyond that we cannot scientifically go. That is why we need philosophy and theology as well as science to understand the reality in which we live. .