The post was removed but not before being captured by Patheos blogger Captain Cassidy and revealed Sampson's apparent struggles with science and "contradictions in the Bible.
"Time for some real talk... I'm genuinely losing my faith.. and it doesn't bother me... like, what bothers me now is nothing... I am so happy now, so at peace with the world.. it's crazy / this is a soapbox moment so here I go xx how many preachers fall? Many. No one talks about it.
"How many miracles happen. Not many. No one talks about it. Why is the Bible full of contradictions? No one talks about it. How can God be love yet send 4 billion people to a place, all coz they don't believe? No one talks about it.
"Christians can be the most judgemental people on the planet – they can also be some of the most beautiful and loving people... but it's not for me. I am not in any more."
The post continues with Sampson saying that he wants to know only the truth and that Christianity had become "like another religion at this point".
"I want genuine truth. Not the 'I just believe it' kind of truth. Science keeps piercing the truth of every religion," he writes.
"Lots of things help people change their lives, not just one version of God. Got so much more to say, but for me, I keeping it real.
"Unfollow if you want, I've never been about living my life for others. All I know is what's true to me right now, and Christianity just seems to me like another religion at this point."
Hillsong could not be reached for comment on Sampson's announcement.
Countless Christians have worshipped God to songs penned or co-authored by Sampson, who first joined Hillsong's worship scene in the 90s.
Popular songs in his discography include "Carry Me", "Better Than Life", "King of Majesty", "For Who You Are", "Take it All", "Came to My Rescue", and more recently "One Thing" and "O Praise the Name (Anástasis)".
The news has saddened many in the Christian scene who were still getting over a similar announcement made a few weeks ago by Joshua Harris, author of I Kissed Dating Goodbye.
Within the space of a week, he announced that he was separating from his wife and that he had fallen away from the Christian faith.
