How Did Christianity End Up With No Notions Of Ritual Impurity?

You need to ritually wash before praying if anything has gone in or out of your body since the last time you were ritually clean. That is, if you’ve eaten, drunk, pissed, shit, vomited, ejaculated, etc.

Item 3 isn’t as out-there as you might think. The eating of shellfish isn’t specifically prohibited in the Quran, but some Muslims avoid shellfish anyway because Mohammed is said to have described shellfish as “distasteful” or “disgusting.”

No, the idea of the mikva has nothing to do with going to heaven. It’s more or less about being able to perform certain actions.