Jude has greeted and he now wraps up his exhortation with an often overlooked phrase. He tells his "beloved" that in order to write of the "common salvation", he had to exhort them to "earnestly contend for the faith", or else there would be no knowledge of that salvation for future generations. But the verse does not end at "faith". He exhorts them to earnestly contend for the faith "WHICH WAS ONCE DELIVERED UNTO THE SAINTS". This has the implication of "once for all". This means that the same faith, that same doctrine of those Christians back then should be ours today. The beliefs that they held should be ours. This does not mean that we should live without electricity because they did, but our stances, God's realness to us, and boldness, should be no different. What is this faith? At its base, it is the gospel: the death, burial, and resurrection for man's sins (I Cor. 1:17, 22-24). There are those today that deny God, and those who believe He is there somewhere but hidden. There are those in false religions based on a natural knowledge of a higher power (Rom. 1:20), and even those who claim Christianity who have tried to fashion Heaven through their own doing. But in this faith once delivered to the saints, Jesus paid it all! The living Word is the basis for the written Word, and it is this Word that men have contended for, even died for, because it cannot change (Gal. 1:6-9; Rev. 22:18-19). An unchanging God (Heb. 13:8) inspired (II Pet. 1:21) an unchanging Bible. Anyone who changes is not only cursed, but has changed it themselves. Those that believe them follow in darkness. We were given an unchanging faith, and still have that same faith. Let us contend for it so that we do not change and others have a chance to hear it, as it is, as well.
"The faith is not what changes. It is man that changes."