He has been speaking as the first 14 children who have come from The Jungle migrant camp in Calais are being welcomed to the UK.
They have been reunited with relatives who are already in Britain.
Rt Rev Jonathan Clark told Premier's News Hour the Church has been vital in turning attention to this issue.
He said: "I think if the Church's voice hadn't been there, it [the call to help these children] would have been a lot weaker.
"The churches have been right at the heart of this in saying that this is something we need to do, as Christian people welcoming the stranger is written into our DNA and this is absolutely essential for us."
The Bishop of Croydon said that being back with loved ones is the start of a long healing process.
"They come with incredible trauma, it's going to be very difficult for them to become children again, having had to deal with all the sort of danger and difficulties they've had."
He told Premier people can be "praying for them in their readjustment, and for their family members as they get to know them again."
UK officials are now in France looking for other unaccompanied young people in a similar position.
Bishop Jonathan said that these children have been through a variety of awful experiences, including trafficking.
He said: "These youngsters have not only been stuck in horror of the camp at Calais, but they've also been generally moved around illegally across Europe as they've been trying to get here - so the chance of being back together is just an extraordinary turn around for them."
Dozens more children are expected to arrive this week after a team of British officials were sent to Calais to help French authorities speed up the transfer of minors ahead of the dismantling of the Jungle.
Listen to Premier's Aaron James speak to Rt Rev Jonathan Clark here:
