"...And from the best ways of dealing with the ignorant is to ignore and avoid them. This is because if you debate with them, they beat you, and if you beat them, they will end up hating you and will not admit your being correct. Therefore, ignore them:
...فَأَعۡرِضۡ عَن مَّن تَوَلَّىٰ عَن ذِكۡرِنَا
"So, avoid those who turn away from Our Reminder..."
فَٱصۡفَحِ ٱلصَّفۡحَ ٱلۡجَمِيلَ ...
"...So, overlook their faults in a beautiful manner."
Avoid them and do not debate them, because debating them puffs up their chests and increases their confidence, and ash-Shafi'i said: "I never debated an ignorant person except that he won, and I never debated a knowledgeable person except that I won." This is because the ignorant one will deny even the presence of the Sun at noon, and will deny the presence of the Moon on a night when it is full!
So, watch the ignorant die if you avoid them, and be given life if you debate them. It might be that they come to their senses if you ignore them, and will realize their status if you are shown to be above debating and discussing with them - this is if you are sure that he is an ignorant follower of desires, not seeking to admit the truth, and not seeking to follow that which is certain..."
['at-Tarbiyah al-Jihadiyyah wal-Bina''; 1/301]
(SHEIKH 'ABDULLAH YUSUF 'AZZAM (ASY-SYAHID, INSYAALLAH)