By the few people who know it exists, the significance of Christian Reformed Doctrine is overrated in almost all ways.
Christian Reformed doctrine is one way to refer to the collected beliefs of the members of the Christian Reformed Church or CRC. It is one part the theology of the theologian John Calvin, one part additions to Calvin, and one part immigrant folkways.
Members of the CRC are mostly decendants of Dutch immigrants. They left the Netherlands because they felt they couldn't worship God in the way that they wanted. Once they immigrated to the U.S., they set up their own churches, schools and communities, creating their own subculture.
What are the Christian Reformed Church's doctrines?
1. There are too many to list them here, but you can come up with a lot of them if you know Calvin's theology semi-decently (relatively orthodox thoughts on the trinity, Christ's divinity/humanity, Christ's death and resurrection, plus a heaping helping of predestination).
2. You'll also want to add in modern evangelical sensibilities: A tendancy to be conservative, sing both old hymns and newer praise choruses, and buy lots of stuff marketed toward evangelicals (WWJD bracelets, t-shirts, Christian Contemorary Music, Frank Peretti books...).
3. Finally, you'll also want to add in the sort of wierd accretions that occur when a group's been around for awhile--a sort of museum of old theological arguments and customs past. The CRC's against lodges. You know them. The Elks. The Moose. The Masons. All those guys. It's too close to a religion from the CRC's view. Similarly CRC folks tend to go to denominationally controlled schools and the denomination's college, Calvin College. Also people try not to mow their lawns on Sundays or buy anything from a store or go to restaurnants. This is a remnant of trying not to work (or make anyone else work) on Sundays, something that's almost impossible in a modern society.
Mind you, I'm not saying that these are all official doctrine. This is just the stuff that people are generally thinking of when they say "Christian Reformed Doctrine." The people who are still part of the church tend to overrate the worth of some of this stuff and the people who aren't tend to overrate the horribleness of it.
Cf. Dutch Bingo, Dutch Mafia, John Calvin, Christian Reformed Church, Reformed Church of America, Calvin College