Justin Bieber and Selena Gomez reconnected after she underwent a kidney transplant.

The 'As Long As You Love Me' hitmaker seems to be on friendly terms with his former girlfriend and it has now been revealed that her health troubles are what brought them back together.

According to The Blast, Justin didn't have her current phone number and had to reach out to her through his friends. Now they are back in touch, they have been bonding over religion and have been attending church together.

It comes after an insider revealed Justin is keen to ''regain'' Selena's ''trust''.

A source said: ''He hopes to regain her trust so they can get back together. They have so much to catch up on. They dealt with things separately this year that made them different people. It wouldn't be surprising if they got back together ... It seems their relationship now is very different. Justin is certainly a much better person. He would be a better boyfriend, too.''

And Justin is keen to show Selena's family how much he has changed.

An insider shared: ''Justin is aware Selena's family is not thrilled they are hanging out. They think he caused Selena a lot of grief. Justin hopes he can prove to them that he has changed. He has changed a lot in the past few months. He is a very different person. They have a lot to talk about and are having fun catching up.''

Justin and Selena dated on and off for four years from 2011 to 2015.