The newly-reunited couple appeared ''smitten'' with one another at the session at City Church in Los Angeles, where they sat quietly with friends and listened to a sermon from Pastor Judah Smith.
A source told Us Weekly: ''They were very lovey dovey and cute. They came and left together with a few friends
''They sat next to each other and listened to the sermon and were smitten with each other.''
And it seems the sessions have been having a positive effect on Justin, following months of controversial antics.
The source added: ''He looks so happy and at peace.''
The 20-year-old singer won back the 'Come and Get It' star - who he has had an on/off romance with since 2010 - after vowing to curb his wild ways and even change his friendship group.
A source told The Sun newspaper: ''He told her he can't live without her and that he's reformed his bad boy ways for good.
''He's ditched a few of the troublesome characters he's been hanging out with after advice from his management.
''And Selena thinks he's being genuine and given Justin another chance.
And as a symbol of his new direction, Justin presented Selena with a £6,000 Segway at his Beverly Hills home so they can have ''good, clean fun'' together.
The source added: ''It was when she agreed to go to his house that he gave her the new, shiny Segway.
''He thought a Segway would be a chance to prove they can have good, clean fun together, and she thought that was a really sweet touch.''
In honour of the arrival of the royal baby...
The Vanity Project reveal the truth about their unique aesthetic.
ATR hit Islington's O2 Academy tonight to fully display their importance to thrilling effect.
These artists are no-one's guilty pleasure.
Rocks was released on this day (May 3) in 1976.
Daughters in the current climate are stronger than ever following last year's You Won't Get What You Want.
Je t'aime Taylor Swift's latest video for her new single 'Me!' featuring Brendon Urie of Panic! At The Disco.
Celebrating the wonders of Jazz music.
With virtually the same blend of wit and idiocy as the 2001 original, this fashion-scene...
Though Derek and Hansel have left the world of fashion modelling behind them, a part...
Derek, Hansel and some other familiar faces are back in Zoolander 2! After offering their...
After a disastrous return to the fashion industry following his retirement, which almost ended in...
When Justin Bieber was discovered by Scooter Braun and Usher Raymond after performing his songs...
Clearly designed with his 12-year-old female fanbase in mind, this backstage myth-making doc wants to...