What is the ruling on dealing with relatives, friends, and neighbors who disbelieve in and insult God – God forbid – and is it permissible to boycott them, greet them, or shake hands with them?

Reviling Allah the Almighty is an act of disbelief that expels one from the fold of Islam. It is permissible to shun those who commit sins if it is highly probable that shunning them will be more beneficial; otherwise, maintaining ties is preferable for the purpose of inviting them [to righteousness]. The parents are an exception to this; it is not permissible to shun them. It is permissible to greet and shake hands with a sinner. As for someone who has committed an act of disbelief and has not repented, greeting them depends on what serves the greater good.