Ranks Of Non-Religious Growing

The millennials — those born after 1980 who began to reach adulthood around the year 2000 — are less likely to claim a religion than their parents and grandparents were at the same age. . . one in four, or 25 percent, do not identify with a denomination or faith. They describe themselves as either atheistic, agnostic or "nothing in particular." Among Generation X, whose younger members were young adults in the late 1990s, one in five, or 20 percent, were unaffiliated. For baby boomers, who were young adults in the late 1970s, that figure was about one in eight, or 13 percent. . . . About 64 percent say they are absolutely certain of God's existence, compared with 73 percent of their elders.

From here.

Europe has experienced a similar trend already, which appears to be stable and permanent, and the steady sustained growth in the share of the population identifying as non-religious is confirmed aby other sources.