Jude 1:3

Ἀγαπητοί recurs in 17, 20 and often in 2 Peter. It is also frequent in 1 John, but there a great many other forms of address are used as well.

πᾶσαν σπουδὴν ποιούμενος γράφειν … ἀνάγκην ἔσχον γράψαι. Distinguish between the use of the present tense in the first clause and that of the aorist in the second: we may infer that Jude was contemplating the writing of a treatise (or more probably an Epistle) on more general lines περὶ τῆς κοινῆς σωτηρίας, when he was suddenly compelled to write at short notice and warn his readers against a special danger. We are reminded of the intention expressed in 2 Peter 1:12-15.

ἐπαγωνίζεσθαι: not common in the sense of defending, which is its meaning here. Plutarch (quoted by Mayor) speaks of the philosopher Cleanthes ἐπαγωνιζόμενος τῇ ἐκπυρώσει, i.e. defending the Stoic doctrine of the destruction of the world by fire.

τῇ ἅπαξ παραδοθείσῃ τοῖς ἁγίοις πίστει. ἅπαξ “once for all,” cf. Jude 1:5 and Hebrews 6:4. παραδοθείσῃ, compare the Pauline use in 1 Corinthians 11:2; 2 Thessalonians 2:15, and the παραθήκη of 1 Timothy 6:20. ἁγίοις. Bodies of Christians are called ἅγιοι in Acts 9:32; Acts 9:41 (at Lydda and Joppa), 1 Corinthians 16:1 etc.

πίστει. Here not the act of believing but the truths believed. Paul preached the faith, τὴν πίστιν, which once he used to destroy (Galatians 1:23). The phrase belongs to a time when a creed (of however simple a kind) was delivered to converts by their teachers: a confession of faith which they were required to repeat in public at the time of their baptism.