What is the ruling on a Muslim man marrying a Christian woman, especially if there are circumstances preventing public marriage and incurring the wrath of parents?

The young man must break off the relationship with the girl and obey his parents in not marrying her. However, if he fears falling into indecency (zina), then he may marry her, and he will not be sinful for disobeying his parents at that point, because there is no obedience to a created being in disobedience to the Creator.