What is a Root of Bitterness? (Hebrews 12:15)

The “root of bitterness” is mentioned in Hebrews 12:15:

See to it that no one fails to obtain the grace of God; that no “root of bitterness” springs up and causes trouble, and by it many become defiled. (ESV)

It is popularly thought that this “root of bitterness” refers to personal feelings of resentment or unforgiveness. While it is certainly true that Christians should not harbour bitter feelings, that is not the meaning of the “root of bitterness” in this passage.

The writer of Hebrews was actually using a metaphor that is found in Deuteronomy 29:18–19:

Beware lest there be among you a man or woman or clan or tribe whose heart is turning away today from the LORD our God to go and serve the gods of those nations. Beware lest there be among you a root bearing poisonous and bitter fruit, ₁₉ one who, when he hears the words of this sworn covenant, blesses himself in his heart saying, “I shall be safe, though I walk in the stubbornness of my heart.” This will lead to the sweeping away of moist and dry alike. (ESV)

In context, Moses was warning the Israelites not to turn away from the true God. Here, the “root bearing poisonous and bitter fruit” describes a person who turns away from God and thinks that he will not suffer any consequences. The imagery of a “root” is used to describe the danger of this person to the whole community: When one person in the community falls away from God, many other people in the community might be influenced to also fall away from God.

The writer of Hebrews used this metaphor of the “root of bitterness” to warn Christians to watch out for people in the church who might fall away from Jesus, as they might “defile” many other people and influence them to fall away as well. This interpretation fits within the larger context of the Book of Hebrews, which repeatedly encourages Christians to continue in faith, and not to fall away from Jesus.