Teen popstars Justin Bieber and Selena Gomez have done nothing to squash rumours their on-off relationship is back on again after attending a Bible study together.

Bieber, who has had several run-ins with the law sparking concerns that he's spiralling out of control, posted a photo on his Instagram page of Seattle's City Church pastor Judah Smith on Wednesday evening.

A source who also attended the meeting told Us Weekly that Bieber and Gomez – who first began dating three years ago – "came and left together with a few friends".

"They were very lovey-dovey and cute," the source added, noting that the pair seemed to be "smitten with each other".

Another insider told Hollywood Life: "Justin has told her [Gomez] that he's changing his ways and she totally supports him and feels like he's finally grown out of that bad boy phase, so they are both in really healthy and positive place right now.

"And what's really been making a difference is that they have both praying together and you can tell what an impact this has been making on the both of them, especially Justin."

Adding fuel to the fire, Bieber tweeted "Love" to his 52 million followers yesterday, leading to mass speculation that he and Gomez are indeed back together.

The 'Baby' singer's faith has been the source of much talk in recent weeks, and he reportedly spent a week studying the Bible with Hillsong NYC pastor Carl Lentz before being baptised in a friend's bathtub earlier this month. He apparently chose the unique location after being unable to find a church where the ceremony could be conducted privately.

He enjoys a close friendship with Lentz and Smith, the latter of whom apparently texts the star Bible verses each day. The three have shared pictures of their time together on social media, and Bieber even posted a video of one of Lentz's sermons on his Twitter account.

Selena Gomez has also shared of her Christian beliefs online, posting an Instagram photo on Easter Sunday from the City Church captioned: "He is risen, @judahsmith just thank you," and has been seen worshiping at the megapastor's church in Seattle.

It seems that Bieber's bad-boy image might be coming to an end – Lentz told CBN in March that he is "a good kid. He's trying to figure this out," while Smith has defended the 20-year-old as "pretty sensational" and "serious about his faith".

"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," Lentz added.