From Merriam-Webster Dictionary:
secular adjective sec·u·lar
1b. not overtly or specifically religious
A secular AA meeting is a meeting of Alcoholics Anonymous with a format that does not promote any specific religion, spiritual beliefs, or concepts of higher power. A secular meeting format does not contain prayers or readings that promote any particular worldview, religious or otherwise. The intention is to create a safe space for recovery from alcoholism that is equally welcoming to Buddhists, atheists, Pagans, agnostics, Muslims, Christians, Hindus, Jews, New Agers, and people of all beliefs and backgrounds.
A secular meeting is all-inclusive, neither encouraging nor discouraging any worldview.
Members and attendees may be atheist, spiritual, religious, or agnostic. They may have spiritual beliefs and concepts, atheist beliefs, or religious ones, and might mention those beliefs in the meeting or might not.