> That's not a matter of rationality anymore; it's faith. There's no evidence either way.

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.

There is no rational distinction between positive and negative assertions in the general case. A positive assertion to a statement is equivalent to a negative assertion for the inverse of the statement. Numbers don't count (ha) because we know facts such as "the set of integers is infinitely large". Your ball color example is just nonsense. You used green but then switched to blue for the negative assertion. Also, that's not how colors work. In the case of religion, you're going off your preconceptions and biases. A religious person could easily say the opposite. You would both be speaking nonsense by saying your bias is more rational.