The Oasis charity headed by Rev Steve Chalke is to host a two-day conference dealing with the issue of same-sex relationships next April.

Organised by the Mesa Partnership, Open Church 2015 will include contributions both from people who do not believe that same-sex relationships are permissible for Christians and from those who do.

Among the confirmed speakers so far are Andrew Marin, president and founder of the Marin Foundation in Chicago; the Bishop of Buckingham, Rt Rev Alan Wilson, who said at Wednesday's PinkNews Awards that he is "ashamed" at the way gay people have been treated by the Church of England; and theologian Tony Campolo, who says he is "conservative on the issue of the Bible and same-sex relationships". Another speaker is Christian recording artist and theologian Vicky Beeching, who recently came out as gay.

The conference will include stories of Christians who have been affected by the issues, including those who have adopted a celibate lifestyle, explorations of wider issues around transsexuality and bisexuality and discussions of the psychological issues that can arise from growing up gay and Christian.

It will seek to address issues of how people who disagree within the Church can still work together, and how it is possible to build inclusive churches.

At an event for journalists last night Chalke said that the Open Church event was "not about changing views, it is about encouraging dialogue, creating a forum that makes dialogue possible".

However, he said that his own position was clear: "Gay people don't find evangelical churches to be an environment in which they feel welcome or can thrive. It isn't possible to believe that gay relationships are sinful and still be truly welcoming. However nicely you say that desire for someone of the same sex is sinful, you're still saying it."

Rejecting the validity of same-sex relationships, he said, "denies a fundamental principle that God is love".

The issue is one which has caused deep divisions within the evangelical movement. Oasis was removed from membership by the Evangelical Alliance following an article Chalke wrote for Christianity magazine in January last year in which he called for "an open and generous acceptance of people with sexualities other than heterosexual". At last night's meeting he said that he had written the article to begin a "gracious conversation" and to make it clear to the Oasis staff – around 5,000 in the UK – and the 25,000 children in its schools and projects that they were valued whatever their sexuality.

Questions were raised about whether the Open Church conference would adequately represent the conservative viewpoint of most evangelical Christians. Chalke said that the list of speakers had yet to be finalised and that he was committed to encouraging dialogue.

The conference will take place on Friday and Saturday, April 10-11 at Oasis' Waterloo headquarters. Early bird and group tickets can be booked here.