Do the family of a Christian man who converted to Islam and died after marrying a Muslim woman and having two daughters inherit from his large estate? And does inheritance exist in Christianity?

An unbeliever does not inherit from a Muslim, based on the Prophet Muhammad's (peace be upon him) saying: "A Muslim does not inherit from an unbeliever, nor does an unbeliever inherit from a Muslim," and there is a consensus among scholars on this matter.

If a Muslim man dies and has no heirs except his Muslim wife and his two Muslim daughters, then his wife receives one-eighth, and his two daughters receive two-thirds as a prescribed share, with the remainder returned to them.