A recent Pew Research Center survey has revealed that the number of Americans who identify as Christian has fallen by 13 million over the last 10 years.

Now just 65% of Americans describe themselves as Christian—down 12% since 2009—while 26% describe their religious identity as atheist, agnostic or “nothing in particular”—an increase of 17% over the last decade.

Although the study doesn’t delve into the particular reasons why so many Americans are choosing to reject Christianity, it does show that the downward trend in the number of American Christians spans far and wide.

“Religious ‘nones’ have grown across multiple demographic groups: white people, black people and Hispanics; men and women; all regions of the country; and among college graduates and those with lower levels of educational attainment,” the study states. “Religious ‘nones’ are growing faster among Democrats than Republicans, though their ranks are swelling in both partisan coalitions.”

“This is sad but not surprising,” Dr. Michael Brown, host of the syndicated ‘Line of Fire’ radio program and president of the FIRE School of Ministry in Concord, North Carolina, told Decision. “For several decades, the church of America has leaned on the arm of the flesh more than the arm of the Spirit, watering down the Word and trying to win the world by becoming like the world, which is always the formula for disaster.”

According to the study, the younger generations are most at risk, with only 49% of millennials (ages 23-38) identifying as Christian.

“We must take this as a wake-up call, a call back to the basics, to our knees, to the power of the Spirit, to a fresh encounter with the Lord, to an uncompromised Gospel,” Brown said. “Back to the basics! That’s the key to a new awakening.”

Christian apologist Alex McFarland similarly told Decision, “We need to view this as an opportunity—an opportunity to recommit ourselves to the Great Commission, a definite opportunity to pray and an opportunity to learn how to share the Gospel. If we seize this moment, it can be a great opportunity for us to recommit ourselves to Christ’s call to make disciples of all people.”