well, actually, God is complete in Himself and doesn't, technically, "need" us at all. He could spend eternity without us and still be happy.
But sin destroys us. I know. I used to be "liberal" in this one particular way, although politically, I was almost always a Republican.. (except when I was a teenager but what do they know?)
Anyway, the Catholic Church and many other non Catholic churches teach that this one sin I used to commit is a very serious sin, but when young, I didn't listen to the CC about that particular thing, which I would rather not identify (no, it wasn't the M thing...) LOL
But now I see the wisdom in all Church teachings. You can't accept just some of what Jesus said... can't be a cafeteria Christian