Police are asking them to come forward if they know anything about Moses John and his mother Pauline Watson who disappeared from their home in Northamptonshire in the summer of 2015 and are thought to be in London.
Fourteen year old Moses has special educational needs and had been at the centre of the family court litigation.
Detectives say it is likely that Ms Watson, who is in her 40s, has attended a church over the past year - and they want church ministers or members of congregations to come forward if they have information.
Moses is black and about 5ft 9in tall. His mother is also black and around 5ft 7in.
"It is likely that Moses' mother has attended church services," said Detective Sergeant Nickie Deeks, who works for Northamptonshire Police. "It may even be that she has asked a clergyman for help or advice."
Police say Ms Watson is from Jamaica and is thought to have links to areas of London including Croydon, Islington, Merton, Sutton, Southwark and Lambeth.
Detective Sergeant Deeks added: "We would urge all clergymen, church ministers and churchgoers - particularly in the London area - to think very carefully about whether they might have seen or had contact with Moses or his mother.
"They may have been faces in a congregation, they may have been at church events, they may have needed help.
"We would urge anyone who thinks that they might have any information to please get in touch.
"It is vitally important that Moses is found."
Social workers also have concerns about the way Moses' mother has behaved towards the teenager.
They say she is thought to have mental health difficulties and has spoken of how she ''hates'' Moses and considers him a disappointment.