What is the ruling on joining a general non-Islamic group on "Facebook" with the aim of spreading the religion and inviting people to Allah, and is that considered cooperation in sin and aggression, and what is the extent of validity of the saying that inviting to Allah is the greatest pillar of the religion?

There is no objection to joining groups for spreading good, as long as there is no direct sin involved, provided that one denounces evil and lowers one's gaze from forbidden things, and leaves the group if it has a negative impact. As for the saying "the Greatest Pole" in religion, it can be used for exaggeration, not absolute preference, otherwise, the greatest pillars of religion are the two testimonies (Shahadatayn) and then prayer.