Places at the Labour leadership hustings due to be held next week by the Christian Socialist Movement (CSM) have had to be increased due to the high level of demand.
The hustings event is unique because it is open to Christians even if they are not members of the Labour Party.
The event will be held on Monday 5 July at Westminster Central Hall.
CSM has been keen to encourage the candidates to talk about the role faith can play in politics. It also feels there has not been enough discussion about the values which motivate each of the leadership contenders, and how those values will actually be applied.
The organisation, which brings together Christians on the Left of politics, also wants candidates to talk about how they will reconnect the Labour Party with local communities.
CSM has also invited members of other societies affiliated to Labour to attend and ask questions on special interest issues such as health and education. As with CSM, many have long histories as part of the Labour movement.
CSM Director Andy Flannagan said: "As the leadership election campaigns progress, the candidates need to look beyond the Labour Party and show how Labour can reconnect with the different parts of our society. That is what this hustings event is all about. It could take the leadership election to a new level of debate.
Stephen Beer, CSM's political communications officer, added: "Churches are active in communities all over the countrty. Labour has had a strong Christian influence running through it since it began. Our leadership candidates will have a great opportunity to show how they will draw from Labour's traditions both to engage with people of faith and to renew the Party."
The candidates campaigning to be leader of the Labour Party are: Diane Abbott, Ed Balls, Andy Burnham, David Milliband, and Ed Milliband. All five will be at the CSM hustings event.
People who want to attend the event need to register with CSM at firstname.lastname@example.org, inserting the word 'hustings' in the subject line of their email. The event takes place at 7.30pm on Monday 5th July at Methodist Central Hall