In the first of the theme verses (vv. 3-4) Jude conveys that he didn’t plan to write the letter as it currently reads. It seems that information about a crisis situation warranted a shift in focus. Jude exhorted his readers in v. 3 to contend for the faith, and this appeal sets the tone of the letter:
Beloved, although I was very eager to write to you about our common salvation, I found it necessary to write appealing to you to contend for the faith that was once for all delivered to the saints
The opening term “Beloved” is an affectionate vocative that reminds the readers of God’s love for them. Jude also refers to them this way in vv. 17 and 20. All three occurrences of the word are at key sections of the letter, so it appears that the word was part of his compositional strategy. Here in v. 3, “Beloved” introduces the theme ideas of the letter.
Jude was eager to write about “our common salvation,” which probably means he wanted to celebrate with them the redemptive work of Christ which saved and secured them. Rather than celebrating salvation at length, Jude spends most of his letter on the warning of judgment on the ungodly (vv. 5-19).
Why the change in emphasis? Somehow (he doesn’t disclose how), Jude learned about intruders who posed a serious spiritual threat. It became clear that the believers in the church(es) were not contending for the faith as they should. So Jude shifted gears. He needed to get right to the point and show them how serious their situation was.
Jude called his appeal a necessity. He didn’t believe he had the freedom to discourse about anything else. A holy compulsion guided his pen.
Though the readers had received God’s peace through the gospel, and though Jude prayed for such peace to be multiplied in their fellowship (v. 2), the circumstances around them were anything but peaceful. So Jude chose the correct verb to reflect the true state of things: “to contend” is an athletic image of wrestling, struggling with, fighting for.
The readers should be engaging in a specialized warfare, contending for “the faith.”
Probably the readers should contend for the faith because of what the intruders are doing to it, and the actions of those intruders help us accurately identify what “the faith” is. The intruders “pervert the grace of our God” and “deny our only Master and Lord, Jesus Christ.”
So what exactly does Jude mean by “the faith”? Most likely he means the gospel. The readers should contend for the gospel because the intruders are contradicting it, denying it, perverting it.
The description “that was once for all delivered to the saints” also supports identifying “the faith” as the gospel. “Delivered” was transmission language, used by Paul in 1 Corinthians 15:3 to refer to the gospel traditions he’d received and passed on.
Jude has just prayed for the blessings and power of the gospel to multiply in their fellowship (v. 2), and now he’s exhorting (“appealing to”) them to take action on behalf of the glorious good news.
At this point he doesn’t elaborate further on what it means to contend, but later in vv. 20-23 he explains the actions he wants his readers to take. The jump from v. 3 to vv. 20-23 doesn’t mean Jude forgot what he was writing about. In a previous post (here), I presented a chiastic arrangement of the letter. By design, then, Jude gives his reason for writing (v. 3) and returns later (vv. 20-23) to expand on the notion of contending for the faith.
The reason for the letter is clear. Jude wrote to make an appeal for the sake of the faith, the gospel. Could the stakes have been higher?