What is the ruling on a ritually impure person (junub) intentionally performing prayer, and does he, by this act, exit the fold of Islam, and what are the consequences thereof?

Purification from both minor and major ritual impurity is a condition for the validity of prayer. Whoever prays without purification, whether intentionally or forgetfully, their prayer is invalid and must be repeated. Scholars have agreed that whoever prays without purification, deeming it permissible or mocking it, has committed an act of disbelief (kufr), and must be asked to repent; otherwise, they are to be executed. As for one who does so out of negligence, Abu Hanifa held that they disbelieve, while the majority of scholars believe that they do not disbelieve, but rather have committed a grave major sin, and must repent, seek forgiveness, and repeat the prayer.