The apostle Paul advises Christians not to leave a marriage partner just because that individual is an unbeliever.
نَصَحَ ٱلرَّسُولُ بُولُسُ ٱلْمَسِيحِيَّ أَلَّا يَتْرُكَ رَفِيقَ زَوَاجِهِ لِمُجَرَّدِ أَنَّهُ غَيْرُ مُؤْمِنٍ .‏