Galatians 1:6-9 (ESV)
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.
The Gospel is more important than the one who delivers it. Paul includes himself in the condemnation of those who would dare to deliver another Gospel. “Even if I deliver another Gospel”, Paul says, “then I should be eternally condemned”.
A couple of thoughts:
1) Paul includes himself in the warning. We should never be so presumptuous that we know with absolute certainty that we will never change or never be less than orthodox. Such self confidence is not faith in the keeping power and love of God. It is faith in oneself. The mark of faithfulness in the power of God to keep us is carefulness.
2) We are not as important as the message we deliver. God could raise up stones to do what He has called us to do and we need to remember that people do not become believers because of how well we deliver the Good News. The Gospel is the power of God.
3) Knowing the facts of the Gospel is crucially important. The nonsense that says we should not get bogged down in the details – just love Jesus – sends people to hell and we should never fall into the sin of it.
4) You will be tempted to fudge the truth and present another Gospel. The issue has always been and always will be, “What is the Gospel?” Today, if the church finally capitulated and said, “yes, all roads do lead to God”, the world would rejoice. And we feel the disapproval of the world when we claim that there is only one way to God and it is through faith in Jesus Christ. We could escape the scorn of the world if we would only change the message. But we dare not. We must not. We cannot.
When you give the Gospel, give the only Gospel there is to give. It is the power of God. It does not need to be apologized for, have parts of it hidden or changed to help people accept it. God saves through the only Gospel there is. Preach it.