What is the ruling on attending a disbeliever’s funeral?

Question 423: Is it permissible for a Muslim who believes in one God to participate in the wedding ceremonies of Mushriks (those who associate others with Allaah in His Divinity or worship), and help them arrange such ceremonies on account of a blood or marriage relationship, or the like? Also, is it permissible to attend their funerals, without praying for their dead, and the burial? Is it permissible to sit and commiserate with them?

Answer: It is not permissible to share in their occasions, which involve Shirk (associating others with Allaah in His Divinity or worship) or Bidd`ah (innovation in Islaam). Moreover, it is not permissible to follow their funeral processions; because this is a type of forbidden association with them... read more here.