Sheikh Al-Islam Ibn Taymiyyah (رحمه الله) said:
People are of three kinds:
1) Those who acknowledge and follow the truth – these are the people of wisdom.
2) Those who acknowledge the truth but do not apply it – these people need to be admonished in to applying it.
3) Those who do not acknowledge the truth- these people need to be argues in a way that is better. Because argument often leads to anger, it must be resorted to in a way that is better, just as one resorts to the best [strategy and way] when one is defending himself from an attacker.
[Majmoo’at Al-Fataawa- 2/45]
Note: The Sheikh is referring to the ayah in the Book of Allaah:
“Invite (mankind O Muhammad صلى الله عاليه و سلم) to the way of your Lord (i.e Islam) with wisdom (i.e with Divine inspiration and the Qur’aan) and fair preaching, and argue with them in a way that is better.” [Surat An-Nahl: 125]