A common mistake that non-christians make is to believe that the people who wrote the bible really believed what they were saying. They did not. They knew full well that they were spinning a web of lies. They also knew that, sooner or later, someone would call them on it. So they put provisions in the bible to shun such dissenters. One of those provisions was the line “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. ” They may well have believed that there were angels in a heaven that might come along to correct their vile falsehoods. That passage ensured that their suckers wouldn’t listen.