Beloved, when I gave all diligence to write unto you of the common salvation, it was needful for me to write unto you, and exhort you that ye should earnestly contend for the faith which was once delivered unto the saints.
Design of the letter (cf. Jude 1:20-21).
All diligence - (2 Peter 1:5.) As the minister is to give all diligence to admonish, so the people should give all diligence to have all Christian graces, and make their calling sure.
The common salvation - wrought by Christ. Note, "LIKE precious faith," 2 Peter 1:1. This community of faith, and of its object, salvation, forms the ground of appeals to common hopes and fears.
It was needful for me, х anangkeen (G318) eschon (G2192) grapsai (G1125)] - 'I felt it necessary to write (at once: aorist: the preceding present infinitive, "to write" х grafein (G1125)], expresses writing generally), exhorting you.' The reason why he felt it necessary 'to write with exhortation,' he states, Jude 1:4, "For there are certain men crept in," etc. Having intended to write generally of the common salvation, he found it necessary, from existing evils, to write specially, that they should contend for the faith against those evils.
Earnestly contend - (cf. Philippians 1:27.)
Once, х hapax (G530)] - 'once for all delivered,' etc. No other faith is to supersede it. A strong argument for resisting heretical innovators (Jude 1:4). Believers, like Nehemiah's workmen, with one hand "build themselves up in their most holy faith," with the other "contend earnestly for the faith" against its foes.
The saints - all Christians, holy, i:e., consecrated to God, by their calling, in God's design.