A.T. Robertson Commentary Jude 1:4

"For there are certain men crept in privily, [even] they who were of old written of beforehand unto this condemnation, ungodly men, turning the grace of our God into lasciviousness, and denying our only Master and Lord, Jesus Christ." — Jude 1:4 (ASV)

Are crept in (παρεισεδυησαν). Second aorist passive indicative of παρεισδυω (-νω), late (Hippocrates, Plutarch, etc.) compound of παρα (beside) and εις (in) and δυω to sink or plunge, so to slip in secretly as if by a side door, here only in N.T.

Set forth (προγεγραμμενο). Perfect passive participle of προγραφω, to write of beforehand, for which verb see Ga 3:1; Romans 15:4.

Unto this condemnation (εις τουτο το κριμα). See 2 Peter 2:3 for κριμα and εκπαλα. Παλα here apparently alludes to verses 14,15 (Enoch).

Ungodly men (ασεβεις). Keynote of the Epistle (Mayor), in 15 again as in 2 Peter 2:5; 3:7.

Turning (μετατιθεντες). Present active participle of μετατιθημ, to change, for which verb see Ga 1:6. For the change of "grace" (χαριτα) into "lasciviousness (εις ασελγειαν) see 1 Peter 2:16; 4:3; 2 Peter 2:19; 3:16.

Our only Master and Lord (τον μονον δεσποτην κα κυριον ημων). For the force of the one article for one person see on 2 Peter 1:1. For δεσποτην of Christ see 2 Peter 2:1.

Denying (αρνουμενο). So 2 Peter 2:1. See also Mt 10:33; 1 Timothy 5:8; Titus 1:16; 1 John 2:22.