"Invite (all) to the way of the Lord with wisdom and beautiful preaching; and argue with them in ways that are best and most gracious: for thy Lord knoweth, best who have strayed from His Path, and who receive guidance."(The Quran 16.125).
Prophet Muhammad [SallAllahu Alayhi Wasallam] is reported to have said:"Halal is clear and Haram is clear; in between these two are certain things that are suspected. Many people may not know whether those items are Halal or Haram. Whosoever leaves them, he is innocent towards his religion and his conscience. He is, therefore, safe. Anyone who gets involved in any of these suspected items, he may fall into the unlawful and the prohibited. This case is similar to the one who wished to raise his animals too close to a restricted area, so that the animals may step into that area. Indeed for every landlord there is a restricted area. Indeed the restriction of Allah are the Haram."(Sahih Bukhari & Sahih Muslim)
"I guarantee a house in Jannah for one who gives up arguing, even if he is in the right; and I guarantee a home in the middle of Jannah for one who abandons lying even for the sake of fun; and I guarantee a house in the highest part of Jannah for one who has good manners.'' (Sunan Abu Dawud)