Beloved, while I was very diligent to write to you concerning our common salvation, I found it necessary to write to you exhorting you to contend earnestly for the faith which was once for all delivered to the saints (Jude 3, NKJV).
Jude challenged Christians with the pressing responsibility to “contend earnestly for the faith.” Why agonize intensely for the faith (the gospel, Gal. 1:11, 23)? Because already ungodly men had slipped in unnoticed, leading souls into sin and unbelief (Jude 4, 5-19). It reassures us to know the gospel was delivered once for all. It is not fluid, changing, modifying itself to the will and wishes of men. “Once” is translated from “hapax” and means once for all. It denotes conclusiveness. There would be no latter-day revelations through visions, dreams, or experiences (Heb. 1:1-2). We contend for a sure and permanent gospel. Scripture describes other things happening “once” (hapax), which confirm the faith-securing truth that the gospel is unchangeable. (1) Jesus suffered for sins once for all (Heb. 9:26). One sacrifice of Jesus is conclusive to redeem sinners. His death does not repeatedly happen (despite the Catholic Liturgy of the Eucharist). (2) Christ’s sacrifice was offered to God once for all (Heb. 9:28). As our High Priest, Jesus offered His blood once for all (Heb. 10:10, 12, 18). (3) We die once (Heb. 9:27). We only experience one physical death. Reincarnation is a fantasy. After death, we will face judgment. Just as Christ died once, offered Himself to God once, and we will die once, the faith (gospel) was once delivered. God delivered the gospel one time for all time. Saints will contend earnestly for it.