Earlier quoted context omitted.
> If we're to be exact, we can't prove that if I throw an object upwards with 5 N of force right now, the gravitational field won't suddenly shift (for some reason) and send it out of the atmosphere. Ok then let’s rephrase the statement to “Absent any sudden shifts in the gravitational field, 5 N of force is not enough to bring a 1 kg sphere to escape velocity.” Science can prove that. And if we can’t prove something…
Ah, but you're overreaching. I agreed with you in the comment you replied to. However, your point about rationality isn't so clear cut in the case of religion. If a religious person tells me that the theory of evolution is just flat out wrong then yeah, I'm going to dismiss that as irrational. If a religious person tells me that people reincarnate or get sent to the afterlife based on their deeds, I personally won't…
If there is no evidence either way, then it is only rational to reject any positive assertion. The reason is that negative assertions are infinitely more likely to be correct than positive assertions. As a motivating example, think of a number between 1 and 1,000. Now, which statement seems more likely to be true: “the number you thought of is 32” or “the number you thought of is not 32.” I have evidence of the number you thought of, but the negative assertion is much more likely.
Another way of thinking about it is this: each positive fact yields are near infinite number of negative facts. E.g. if you know a ball is green then you also know it’s not red and it’s not blue, etc. the converse isn’t true. When you know a negative fact, you learn very little. E.g. what else can you say after learning a ball is not blue.