Muslims are encouraged to be sociable in order to be able to communicate the message of their religion both by their deeds and their words. Therefore, attending meetings and gatherings with non-Muslims is not prohibited in itself, but what is prohibited is to participate in falsehood and disbelief.

answering this question, AMJA Permanent Fatwa Committee stated,

If these meetings mainly aim to rehabilitate addicts psychologically and medically by means of medications and ordinary ways, and the invocations to other than Allah (directed during some of such meetings) are just personal acts performed individually and are not basic section of the program, this will be a sort of legal treatment, and there will be no blame on a Muslim to attend such meetings, provided that he or she is to avoid such invocations to other than Allah and the like.

however, if invocations to other than Allah is an obligatory item in the meeting agenda and is a basic and all-inclusive part of the program, it is impermissible for a Muslim to attend such meetings if he or she cannot avoid them, because this includes two abominable actions: participating in invocations to other than Allah, which is a grievous falsehood, and attending gatherings of evildoing, which is a definitely abominable action.