The first time I heard a Catholic friend refer to a fellow parishioner as a cafeteria Catholic, I had to have the term explained to me. It was used as a mild pejorative, and in a way that was meant to convey disapproval for someone who was perceived to be picking and choosing which doctrines and practices of the church to accept, in the way one would go through a cafeteria line selecting some dishes and rejecting others.
I have now also heard people talk about cafeteria Mormons, and I’ve wondered if it is legitimate for us to borrow the term. I have concluded that it is not. In the first place, it lacks the catchy alliteration the Catholics get. But there is a larger, more important reason, and it is one of the great secrets of the church. Lean in closer, and I’ll whisper in your ear.
Psst! We are ALL cafeteria Mormons.
It’s true. We believe in a religion that believes in doing, and there is so much to do that we simply cannot do it all. Today is Saturday morning, so let’s say I decide to do some missionary work with my neighbor on the golf course. Or maybe we’ll go fishing so he can help me with our food storage. Either way, I have chosen not to support my quorum in the moving project, and I have also neglected the scouts on their camp-out. If you decide to serve in the temple on Thursday night, you need to know that some of the Young Women (or their parents) will notice that you chose not to attend their talent show. Doing research in the Family History Library? Tut tut. Surely you must have known that the cub scout pinewood derby was taking place just across the hall and they could have used your support.
It is my belief that God offers us many good things through His church, and He expects us to be wise enough to choose what we need. Only a very foolish diner would load his tray with one of everything from the buffet line, and someone who insists on doing everything in the church all at once will find that the church is happy to provide a chauffered limo ride straight to the front door of the mental hospital. There is a reason the scriptures admonish us to do things in wisdom and in order, and to be careful about running too fast.
If we think of the church as a cafeteria where all are welcome to join in the meal, we can immediately put down the heavy burden of judging others. You might choose the lasagna, I might choose the salad bar, and our neighbor might bring lunch in a brown bag. Those are all good choices, and we should be able to sit at the same table and enjoy our meals and each other’s company. The apostle Paul’s admonition about the milk and the meat can also be read as an endorsement of the cafeteria model. You might be hungry for a double helping of rare prime rib, while I am only able to tolerate a small glass of skim milk. We can still sit next to each other and sustain one another, and we will have plenty of things to talk about besides what is on our respective trays. And I think we need to be especially careful with the more difficult doctrines. It seems to be simply part of the human experience that, sooner or later, we all need to take a big bite of the mystery meat. I might choose the standard, cafeteria-issued breaded surprise. You might bring a liverwurst and onion sandwich from home. It would behoove us both to charitably refrain from speculating about the origin of our dining partner’s main dish.
At general conference in October, 1953, J. Reuben Clark, a member of the First Presidency, said this:
“I believe that our Heavenly Father wants to save every one of His children. I do not think He intends to shut any of us off because of some slight transgression, some slight failure to observe some rule or regulation. There are the great elementals we must observe, but He is not going to be captious about the lesser things.” 
Still not convinced? Then you need to consider these words from apostle and my fellow cafeteria Mormon, Bruce R. McConkie:
“You don’t have to live a life that’s truer than true. You don’t have to have an excessive zeal that becomes fanatical and unbalancing. What you do have to do is stay in the mainstream of the church – keeping the commandments, paying your tithing, serving…and loving the Lord…” 
So, I hope you join me in the cafeteria. Sometimes the chow ain’t bad.
Conference report, 3 Oct 1953, p. 83
The Probationary Test of Mortality. Devotional address given at the University of Utah institute of religion, 10 Jan 1982.