If you recall what was the "purpose" of life promised in the paradise? Eat, music, art, pets, learning new things, enjoy the company of friends, and make a home. Its what we want, what we need so it was attractive. They never promised a 'purpose' beyond that. The 'serve God' element was undefined and nebulous.
What generally kept us from existential malaise, when the religion was working for us, was "the program", the duties, the sense of selflessness of giving our time.
Some military veterans feel similarly, their former life was structured and in many ways defined by a command hierarchy. Many counselors recommend simple things like getting involved with the community, join a club, do volunteer work, anything to rebuild an identity and learn that life's "purpose" is exactly what you are doing that occupies your mind and fills the heart.