Justin Bieber's one-time pastor Carl Lentz has come clean about his exit from the popular Hillsong Church East Coast, confessing he was fired for cheating on his wife.

Church officials cut ties with the spiritual leader, who served as a mentor to Bieber in the mid-2010s, this week, announcing Lentz's position at the New York City branch had been terminated due to "moral failures".

Now the 41 year old has opened up about his departure in a candid message to his Instagram followers.

"I was unfaithful in my marriage, the most important relationship in my life and held accountable for that," he wrote. "This failure is on me, and me alone and I take full responsibility for my actions."

"I now begin a journey of rebuilding trust with my wife, Laura and my children and taking real time to work on and heal my own life and seek out the help that I need (sic)," he continued.

Lentz went on to add that he was "deeply sorry for breaking the trust" of his congregation.

The pastor joined the New York church location in 2010, and in 2014, Bieber briefly lived with Lentz while he sought his spiritual guidance.

He also helped the singer work through his break-up from Selena Gomez in 2017.

Bieber, now a devoted Christian, wed model Hailey Baldwin in 2018.