Postulates that fit the available evidence are often true
In say, the terry schiavo case, pulling the plug is made legal by the government because of the scientific finding about the state of the brain. Religious people disagreed. Now, the point was that merely pointing at the disagreement is useless--it's an attempt to turn the debate into one about hypocrisy instead of one about whether in fact the brain is in such and such state. They both claim truth, but they do so in different ways, and that difference is the significant one.
If something is just a best guess, it's just a best guess...the leap of faith would be the part that's without foundation.
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