return to the fold come back to the community of beliefs or principles you originally belonged to, having previously repudiated it.
☞ The image is of a lost sheep returning to its fold. It can be expressed in various other wordings (e.g. 'They welcomed him back to the fold').
2004The Cherwell Magazine Online Blair's sudden rush to get it onto the statute books in time for the 2005 election is a shrewd political manoeuvre designed to encourage the party faithful, many of whom were alienated over Iraq, to return to the fold.