The Solomon Islands Christian Association says the government is not considering the impact of another casino on locals.
Its general secretary, the Reverend Eric Takila, says SICA is opposed to the government granting a third casino license.
The Constantinou Group of Australia bought the land of the National Arts Gallery in Honiara this year to build a five star hotel that is to include a casino.
He says having casinos may appeal to some tourists but it perpetuates gambling and other social problems among locals.
"I don't know the rationale behind it but the country is going through a process of rebuilding. We should look at building an economy based on other things, like agriculture and fisheries and not make shortcuts by building casinos."
Reverend Eric Takila of the Solomon Islands Christian Association