Being Hardened By Sin?

October 22nd, 2025
by Lance Waldie

Hebrews 3:13 But encourage one another day after day, as long as it is still called “Today,” so that none of you will be hardened by the deceitfulness of sin.

Now instead of falling away from God, the audience was to “encourage” (Gr. parakaleō) each other day-by-day. To “encourage” is a term used for the Holy Spirit—the Spirit of God who comes alongside another to help, advocating on their behalf like a lawyer to defend. Verse 13 thus exhorts Christians to hold each other accountable, to remain strong in trusting the Lord God. Since it is easy to allow one’s heart to grow cold, followers of Christ need each other to keep to stay sharp, to keep alert, and to warn of the dangers of falling away from the living God.

Psalm 95, quoted in 3:7-11, is again cited with special emphasis placed upon “today.” While it is still called “Today,” there must be encouragement to all who profess faith in Christ to keep them on the road of faithfulness. The writer is not convinced that his audience as a whole is saved, and he did not attempt to put their minds at ease with once saved, always saved. He was concerned that the “deceitfulness of sin” was having its way within the Church. Since the term “deceitfulness” (Gr. apatē) relates to something that is untrue—to trickery in relation to “sin” (Gr. hamartia). The author says that the deceitfulness of sin has the power to “harden” (Gr. sklērunō) a professed believer in Christ. The term refers to someone who has become stubborn or inflexible. If one has a condition with the term “sclerosis” in it, they suffer from the hardening of some soft tissue. There is Atherosclerosis (hardening of the arteries), Amyotrophic lateral sclerosis (Lou Gehrig’s disease), Focal segmental glomerulosclerosis (kidney disease), etc. The deceitfulness of sin within Christ’s Church is actually more fatal than any physical disease dubbed “sclerosis.” Whereas a physical sclerosis will cause physical death, spiritual sclerosis results in eternal death. The latter is caused by the “deceitfulness of sin”—a mindset within the Church of Jesus Christ that causes a professed believer to fall away from the living God.

It could be that there was a false teacher among the brethren teaching them not to be concerned with falling away from their faith, to embrace the lie that Jesus was not superior to any and all things. More likely, it was a small group within the larger group that were becoming more and more convinced that Jesus was inferior to angels, to Moses, etc. This in itself had burgeoned into an all-out heresy that deceived the Church into believing that if they just watered down their faith a bit, they could escape persecution. The deceitfulness that had permeated the Church was causing many of its members to take God lightly and therefore believe the erroneous teaching that Jesus was somehow inferior to angels or to Moses. Yet Jesus is inferior to no one and nothing! He is God Almighty, Creator of heaven and earth (cf. 1:1-4).

Now for those who take sin seriously, who “hold fast the beginning of our assurance firm until the end…” they have “become partakers of Christ.” And partakers are those who are yoked with Christ – brothers of Christ – whose salvation is assured in their perseverance to the end.

Food For Thought
The worst, most dire sin is the sin of unbelief, for it leads to eternal destruction. And unbelief doesn’t just rear its ugly head in atheists, it’s common among professed Christians! For some of them believe in Jesus, yet they take Him lightly or are apathetic towards Him. Truly, unbelief is the most offensive sin to God. Most don’t consciously fight against God or outwardly detest Him; rather, they ignore Him by refusing to commit to Him. Jesus said, “If you abide in My word, then you are truly disciples of Mine” (John 8:31). Commitment to Christ as Lord is the difference between mere profession of salvation and true possession of the living God.