Jude 1:3-4 - Jude's Purpose In Writing
3 Dearly loved ones, as I was very eagerly planning to write to you about the salvation we share in common, I felt it necessary [instead] to write urging you to contend earnestly for the faith [i.e., the teaching of Christ] which was once and for all delivered [by the apostles, See verse 17] to the saints [i.e., God's holy people]. 4 For certain men have secretly infiltrated [your ranks]; they are men who had been written about long ago that they should be judged [and condemned] for perverting the unearned favor of our God into [a license for] living unrestrained, indecent lives, and who deny [the identity and work of] our only Master and Lord, Jesus Christ.