What is the ruling on a Muslim man marrying a Christian woman who had a sexual relationship before marriage? Is their marriage considered invalid and will their child be punished for it?

Whoever believes in a prophet must believe in all prophets, for they are all brothers, confirming one another, and leading to the One, Unique God, without making distinctions between the messengers. Marriage is legally valid if the wife is chaste and free from adultery at the time of marriage, even if she committed immorality in the past and repented from it. Her son from this marriage is a legitimate son. Embracing Islam removes these questions, for there is no fear or grief for those who follow God's guidance.