Is There an Age of Accountability?

In southern baptist christian circles that i grew up in, there was also this teaching. This idea that y children that die before a certain age of accountability go straight to heaven because they have not reached this age of accountability. And and so this is the crazy sort of loophole in the original story. It doesn't seem to make sense to me. If we're all born with original sin, how is it that doesn't kick in until i turn eight, nine or 13 and soo. So here's the other thing that's crazy, even more crazy about that doctrine is that if you really believe that the best thing christians could do would be to start murdering children before they turned