They affirmed their stance on the issue at Mount Olive Missionary Baptist Church on Chicago's West Side.
Last week, State Senate executive committee approved a bill authorizing gay marriage, but due to the short lame-duck session schedule and some lawmakers who were not in attendants, proponents could not bring the bill for a floor vote.
The clergy members say they are disappointed in the bill's supporters who spoke at their churches while they ran for office.
"Those politicians who come to our congregations and profess to be Christians, now they're trying to pass this and legalize this and we are against it," Kenneth Giles, Mt. Olive Missionary Baptist Church.
President Obama and Mayor Rahm Emanuel have urged the general assembly to legalize same-sex marriage in Illinois.