Another Gospel

We see that those who preach any other gospel than Pauls gospel, Paul advices as to treat them as if they were accursed.

(Galatians 1:6-12 [KJV])
 [6] I marvel that ye are so soon removed from him that called you into the grace of Christ unto another gospel:
 [7] Which is not another; but there be some that trouble you, and would pervert the gospel of Christ.
 [8] But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
 [9] As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received, let him be accursed.
 [10] For do I now persuade men, or God? or do I seek to please men? for if I yet pleased men, I should not be the servant of Christ.
 [11] But I certify you, brethren, that the gospel which was preached of me is not after man.
 [12] For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ.

So how do we treat someone as if he is accursed. We avoid him (Joshua 6:18).

We should not even preach the gospel to them.

See also