Who was that written to? Paul starts out by saying “my brethren”. He was writing to those believers who were following the gospel as he preached it to them. What about those who preached “another gospel”?
“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. 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.” Galatians 1:8-9
2 John 1:9 Whosoever transgresseth, and abideth not in the doctrine of Christ, hath not God. He that abideth in the doctrine of Christ, he hath both the Father and the Son. 10 If there come any unto you, and bring not this doctrine, receive him not into your house, neither bid him God speed: 11 For he that biddeth him God speed is partaker of his evil deeds.
Not all who claim to be are "brethren".
I've notice a distinct characteristic of those who seem to be your "brethren" CB (af_vet_1981 doesn't fit the pattern), that characteristic seems to be the unconscionable ability to engage in falsehoods...