I am astonished that you are so quickly deserting him who called you in the grace of Christ and are turning to a different gospel— not that there is another one, but there are some who trouble you and want to distort the gospel of Christ. But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed. As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed. (GAL 1:6-9 ESV)
Can you imagine the voices of outrage if this were said in the midst of an interfaith meeting before the government today? And yet, Paul does not say this out of a sense of superiority or contempt, but out of true compassion and concern. Without the true gospel we are lost, plain and simple. To tolerate or compromise it out of a desire to “come together” with others is to lose the one and only power for the salvation that all faiths claim they want.
For the sake of the world, let anyone preaching a different gospel be cast out and shut down. The preacher of a false gospel is no friend of God or man.