Scientific knowledge is not a collection of subjective opinions. Rather, it is a collection of explanations about objective reality that is based on observed or predicted phenomena. In addition, the explanation must be verified repeatedly to confirm that it correctly models reality.
As our technical ability to observe reality improves, we are able to increase the quality and quantity of our observations. Better-observed data challenge our explanations, some of which will no longer fit the observed facts. New theories are then formed and either verified or falsified.
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In contrast, religion denies the evidence in order to keep their "faith" and traditions intact and has no interest in testing the veracity of their beliefs.
to James Brown: you cited the example of blood-letting in connection with G. Washington's death in order to poke holes in science. Well, guess what? The reason blood-letting is not practiced anymore is because science reevaluated the evidence and moved on as knowledge increased.
What progress has religion made since Washington's time? Or since religion was invented, for that matter?