Hebrews 3:12-4:8

The Concern: Beware of an Evil Heart of Unbelief

The author of Hebrews introduces the warning with urgency: "Beware, brethren, lest there be in any of you an evil heart of unbelief in departing from the living God." This is a concern about apostasy—a falling away from the living God. Apostasy stems from an evil, unbelieving heart.

The author addresses the entire congregation as "brethren" because only God examines the heart. This warning does not imply that a true, authentic believer in Christ risks totally falling away from salvation. Instead, it targets those who outwardly profess faith but inwardly lack genuine belief.

Beware, brethren, lest there be in any of you an evil heart of unbelief in departing from the living God. (Hebrews 3:12)

These individuals may attend church, enjoy fellowship, and even engage in evangelism, yet they do not truly believe the gospel. Apostasy reveals an unbelieving heart beneath the mask of Christianity. The Word of God pierces through outward displays to expose the heart.

As 1 John 2:19 explains:

They went out from us, but they were not of us; for if they had been of us, they would have continued with us; but they went out that they might be made manifest, that none of them were of us. (1 John 2:19)

True apostasy shows they were never truly of us. Salvation comes by authentic faith, not mere profession.

The warning is twofold: Ensure such a person is not in your midst—a little leaven leavens the whole lump—and examine your own heart to confirm it is not you harboring unbelief that leads to falling away.

The Comparison: Belief Versus Unbelief

The text contrasts those who enter God's rest through belief with those who do not due to unbelief. The Israelites in the wilderness heard the gospel but did not mix it with faith.

For indeed the gospel was preached to us as well as to them; but the word which they heard did not profit them, not being mixed with faith in those who heard it. For we who have believed do enter that rest. (Hebrews 4:2-3a)

Scripture repeatedly shows this dichotomy: Abel offered by faith, while Cain relied on his works (Hebrews 11). Jesus' parable of the sower illustrates heart conditions—rocky soil receives the word with joy but falls away in trial, while good soil bears fruit with perseverance (Luke 8:5-16).

In John 6, thousands followed Jesus for bread, but when He preached hard truth, most left, leaving the twelve. Trials expose the unbelieving heart, as with the Israelites at Marah and Massah, who tested God despite His provision.

Today, if you will hear His voice, do not harden your hearts as in the rebellion. (Hebrews 3:15; cf. Psalm 95)

True faith perseveres; superficial belief fades.

The Solution: Exhort One Another Daily

Rather than sin-sniffing, the remedy is mutual exhortation: "But exhort one another daily, while it is called 'Today,' lest any of you be hardened through the deceitfulness of sin."

But exhort one another daily, while it is called "Today," lest any of you be hardened through the deceitfulness of sin. (Hebrews 3:13)

The Greek parakaleo means to call alongside—like the Holy Spirit, the Paraclete. This involves daily encouragement, admonition, and exposure of sin within close relationships. It is not a weekend hobby but a commitment disrupting personal bubbles.

In a healthy church, believers exhort one another daily, fostering perseverance and exposing unbelief or hardening by sin. God also purges His church, as He did in the wilderness, where the unbelieving generation's corpses fell.

This exhortation is for the entire congregation, not just leaders.

The Consideration: The Promise of Rest Remains

Despite the warning, hope endures: "Therefore, since a promise remains of entering His rest, let us fear lest any of you seem to have come short of it."

There remains therefore a rest for the people of God. (Hebrews 4:9)

The Israelites failed to enter due to unbelief and disobedience—genuine faith produces obedience. The gospel was preached to them, yet without faith, they did not profit.

God's rest is not merely a day like the Sabbath or Joshua's conquest, but a state entered by believing the gospel. It remains available today.

For we who have believed do enter that rest... Today, if you will hear His voice, do not harden your hearts. (Hebrews 4:3, 7)

Three Key Applications

Healthy churches are gospel-centered, prioritizing God's glory and mutual encouragement over selfish desires.

Encouragement is a commitment, not a hobby—calling one another alongside without self-righteousness.

Believe the gospel today. Enter God's rest through authentic faith. Exhort one another daily while it is called "Today," holding fast in perseverance.