2:221 Do not marry unbelieving women (idolaters) until they believe; a slave woman who believes is better than an unbelieving woman even though she allure you. Nor marry (your girls) to unbelievers until they believe: a man slave who believes is better than un unbeliever even though he allure you. Unbelievers do (but) beckon you to the fire. But Allah beckons by His grace to the Garden (of Bliss) and forgiveness and makes His Signs clear to mankind: that they may celebrate His praise.
It is sinful to revile a Muslim and to fight with him is to disbelieve. (Bukhari & Muslim)