However, unlike Atheists and perhaps Agnostics, Christians, Muslims, Buddhists can have an extra incentive to fake results.

If you mean to say that Christians, Muslims & Buddhists have incentive to fake results to suit/support their religious beliefs, then atheists have the same problem. Their "extra incentive" would be to fake results to undercut evidence that might lend supports to any of those same beliefs, at every opportunity.

Swap Indian Jones with Richard Dawkins, and tell me that, upon discovering the ark or the grail, he wouldn't have just re-hidden the artifact, and never said a word about it to anyone...