Justin Bieber is on a two-week break in the luxurious Rancho Mirage resort outside Palm Springs, California – but it's not the luxury that he's there for.

The star is spending time with Hillsong pastor Carl Lentz, who has become a mentor to him as he has struggled to overcome his issues with drink, drugs and other challenging behaviour.

According to gossip website TMZ, he has "exiled himself" from friends, alcohol and marijuana during the retreat. He was pictured reading the book Occupy All Streets, the study guide to a programme taught by Lentz aimed at teaching students "to see themselves how God sees them, as agents for change in His kingdom".

Lentz has previously said of Bieber to CBN: "I love Justin, he's a good kid. He's trying to figure this out ... People who are like, 'Is he even a Christian?' With Justin, I tell people grace and acceptance does not mean approval. I can accept you as a human being and not approve of your actions. That's how we've been loved. We love because we were first loved... With Justin, it's not my job to be his police officer. It's my job to be a friend to him, and that's all I am."