Mark 10:12
And if a woman divorces her husband and marries another man, she commits adultery."

1 Corinthians 7:12
To the rest I say this (I, not the Lord): If a brother has an unbelieving wife and she is willing to live with him, he must not divorce her.

1 Corinthians 7:14
For the unbelieving husband is sanctified through his believing wife, and the unbelieving wife is sanctified through her believing husband. Otherwise your children would be unclean, but now they are holy.