There are plenty of scriptures in the bible that state who the true worshippers would be. All who believe Jesus is the messiah, all who love one another and even thier enemy, all who help gods followers , those that help the sick and needy, those that proclaim Jesus is the messiah etc.
Paul stated in 1 Corinthians that the righteous would come out of each sect, so he wasn't claiming any peticular sect would be gods only organization.