The sociological data is clear: Christianity is on the decline in the United States. The decline is not limited to one “type” of Christianity (though it is more drastic in some than others), nor is it limited to a particular race, gender, or age. It is pervasive, but the most significant loss of faith is occurring in the Millennial generation. Only 56% of Millennials identify as Christians. Larry Barnett of The Next Generation Project (TNGP) sought to discover the cause.
Using three large representative data sources, he discovered that doubt is the major reason people are abandoning their Christian faith. Christians who report having little or no doubt regarding the truth of Christianity are the most likely to be confessing Christians, regardless of age. Millennial non-doubters are just as likely as all other generations of non-doubters to be confessing Christians. Those who harbor significant doubts about the truth of Christianity, however, are more likely to abandon their Christian faith. Age is a significant factor among the doubters, with Millennial doubters being much more likely to abandon Christianity than older Christians.