James McConnell, 78, preached the sermon at Whitewell Metropolitan Tabernacle church in northern Belfast in 2014 - one of the biggest churches in the nation.
Mr McConnell, from Shore Road, Newtownabbey, Co Antrim, is being prosecuted under the 2003 Communications Act.
He is charged with improper use of a public electronic communications network, and causing a grossly offensive message to be sent by means of a public electronic communications network.
Mr McConnell denies the charges against him.
He will give evidence at Laganside Magistrates Court.
A Muslim scholar is one of the pastor's defence witnesses, as well as a Catholic priest and DUP politician.
Joe Rice, Mr McConnell's defence lawyer, speaking before the trial, said that: "In this landmark case in defence of freedom of speech I am delighted that we are able to rely on the support of people from many different backgrounds.
"They will accompany my client into court and they have all offered to give evidence for the defence.
"We have built a rainbow coalition on this massively importantly issue.
"We are heartened that those from so many faiths and none have laid aside theological differences to join together in support of freedom of conscience and freedom of expression."
The trial is expected to finish by the end of the week.
