What should I tell a Christian friend who wants to marry a non-Christian?

Josef Pavliňák has been serving university students in the highly atheistic country of the Czech Republic for over 30 years with a ministry called Integrity Life, serving as the director. His heart is to reach out to the students in Central Europe with the gospel, disciple those who become Christians, and develop leadership potential in those who are called to become leaders. Josef has a degree in civil engineering from Brno Technical University. He has lived in the Czech Republic all of his life and is married to his best friend and ministry partner Danka, and they have two adult children – Dominika and Daniel.