Is it permissible for a young Muslim man who is already married to marry a Christian woman by an urfi (customary) marriage without the knowledge of his first wife, knowing that the Christian woman has no guardian and he hopes that she will convert to Islam?

It is forbidden for a Muslim man to have a relationship with a foreign woman, and he must repent and sever this relationship. It is permissible to marry a woman from the People of the Book, provided that she is chaste and truly belongs to a heavenly religion. The permission of her guardian or whoever acts on his behalf is a condition, as well as the fulfillment of the conditions and pillars of marriage. However, marrying a woman from the People of the Book is not preferable due to the many pitfalls it entails, and it is better to marry a Muslim woman. Whoever desires polygyny must be just. And whoever fears the dispersion of his family by marrying a second wife is not advised to do so. As for passionate love, it has a known remedy.