The conference claims to speak on behalf of 35 million Anglicans which it says are outraged by what they see as liberalism attacking their spiritual practices.
In a statement, Gafcon accused churches in the West of proclaiming "a false gospel [that] undermines the authority of God's word" and promotes a "variety of sexual preferences and immoral behaviour".
"We grieve for the spiritual decline in the most economically developed nations, where the forces of militant secularism and pluralism are eating away the fabric of society and churches are compromised and enfeebled in their witness."
Peter Jensen, the archbishop of Sydney, said a Primate's council - a body of the heads of member Anglican churches - would be formed to regulate this "turmoil".
Richard Kirker, who heads the Lesbian and Gay Christian Movement, told Al Jazeera he thought the Anglican conservatives appeared to be declaring themselves "superior in their own eyes".
"I think those who are meeting at Gafcon in Jerusalem have distanced themselves from the rest of us ... and that's very unfortunate." he said.
Divisions within the church spilled over in 2004 when Gene Robinson, the bishop of New Hampshire in the US, became the first openly gay cleric to be made a bishop.
Nigerian Archbishop Peter Akinola, a driving force behind Gafcon, rejected the idea that the conservatives were forming "a church within a church".
Akinola has in the past criticised Rowan Williams, the Anglican church's spiritual leader to whose authority Gafcon is a major challenge.
While the conference's declaration did not mention Williams by name, it said the Anglican leadership had done nothing to discipline the Episcopal Church - the US Anglican body - over the ordination of Robinson or the Anglican Church of Canada for blessing same-sex marriages.