What specific evidence would people require to believe in God's existence?

The evidence for God ought to be stronger than the kind of evidence that Children have for the tooth fairy. The evidence for God ought to be stronger than the kind of evidence children have for Santa Claus. That is to say, the evidence should not depend on what could be faked, or could have been faked by scripture writers.The evidence for God should be stronger than the evidence for the placebo effect. That is, there should be better evidence than can be accounted for by human psychology, self-delusion, self-hypnosis, etc.The evidence for God should be stronger than the evidence for the emperor's new clothes. That is to say, it should be more than the effects of mob psychology.When we say it is a matter of faith, we admit that the evidence does not meet these requirements.

I'm not sure why you find that confusing.I'll use the term "gullibility" for what you are calling "credulous attitude."It is to be expected that the degree of gullibility will vary from person to person. If you could quantify it, then it would probably fit a normal distribution. (By the way, have psychometricians defined and developed as scale for gullibility quotient?)Assuming that there is a range of gullibility it seems entirely expected, at least to me, that religions would tend to be adopted by the most gullible. Thus we would expect religious people, on average, to be significantly more gullible than the population as a whole.Note that I am not denying that some people may adopt a religion on an essentially rational basis. I don't presume that gullibility is a prerequisite. But I do suggest that gullible people are more likely to become religious, much as gullible people are more likely to be taken in by scam artists.

If you have huge congregations of people yelling "Rah, rah, go scientists, go," it won't make the science any better. It might make it worse.Science isn't in the "saving souls" business. It is in the business of finding out what we can about our world. Scientists should do science, not evangelism.

If the administration becomes too unfriendly to science, then scientists will migrate to other nations. You would see a big brain drain. Eventually the U.S. economy would collapse, as the innovation moves elsewhere.Hmm, that might cause some discomfort for the world - a huge economy collapsing, while still in possession of a vast arsenal of WMD.