Our culture is so infiltrated with this notion: "There are many ways to God." Yet, if we take the authority of the Bible literally, there is no possibility for this to be true. Either we have a gospel that evolves & is subject to enlightening or there is only one gospel & it does not change.
I recall a time in college when my fear of a teammate's opinion kept me from speaking the truth of the gospel. I can still remember the situation when he approached me & began to inquire of my interest in religion/theology. Although I was typically quite courageous, something about him made me want him to approve my opinion rather than hear the truth (fear of man vs. fear of God). It was not that much different than Peter's behavior in Galatians 2 that was so worthy of rebuke. I will spare you the details, but lets just say that I blew it. Because, there is only one gospel. What is so deceiving is when false teachers pervert the gospel.
John Stott helps us recognize the true gospel. He offers two tests: its substance (what it is) & its source (where it comes from).
Test 1: "It is the gospel of grace, of God's free & unmerited favour. To turn from Him who called you in the grace of Christ is to turn from the true gospel. Whenever teachers start exalting man, implying that he can contribute anything to his salvation by his own morality, religion, philosophy or respectability, the gospel of grace is being corrupted. That is the first test. The true gospel magnifies the free grave of God."
Test 2: " The true gospel is the gospel of the apostles of Jesus Christ, in other words, the New Testament gospel...Any system 'other...than', or 'contrary to', or 'at variance with' this apostolic gospel is to be rejected."
In closing, Dr. Alan Cole states it best, "The outward person of the messenger does not validate his message; rather, the nature of the message validates the messenger."