"See to it, brothers and sisters, that none of you has a sinful, unbelieving heart that turns away from the living God." (Hebrews 3:12)
Jesus is worthy of greater honour than Moses, as the builder of a house has greater honour than the house itself. Moses was faithful as a servant in all God's house, bearing witness to what would be spoken in the future. But Christ is faithful as the Son over God's house, and we are his house if we hold firmly to our confidence and the hope in which we glory. The comparison is not a dismissal of Moses, whom the author respects deeply, but a demonstration that the one who gave Moses his mission is now present in person. The shadow gives way to the substance; the servant gives way to the Son.
The author then applies Psalm 95, the warning against Israel's failure in the wilderness: today, if you hear his voice, do not harden your hearts as Israel did at Meribah. Who were those who heard and rebelled? Were they not all those Moses led out of Egypt? And with whom was God angry for forty years? Was it not with those who sinned, whose bodies perished in the wilderness? And to whom did God swear they would never enter his rest if not to those who disobeyed? So we see that they were not able to enter because of their unbelief.
See to it, brothers and sisters, that none of you has a sinful, unbelieving heart that turns away from the living God. Encourage one another daily, as long as it is called today, so that none of you may be hardened by sin's deceitfulness. The Catechism identifies the hardening of the heart as the one spiritual condition that makes grace unable to penetrate: not the greatness of sins committed, but the refusal to receive mercy when it is offered (CCC 1864). The warning is urgent precisely because the community being addressed has received enormous grace and is in danger of abandoning it.
Brothers and sisters, encourage one another daily, as long as it is called today. The daily encouragement is the antidote to the gradual hardening that sin produces. You cannot harden a heart that is being warmed daily by fraternal encouragement. Find the person in your community who is drifting and speak a word of encouragement today. Tomorrow may be too late for today's softening.
Lord Jesus, apostle and high priest of our confession, make us faithful over your house. Do not let any of us develop a sinful, unbelieving heart that turns away from the living God. Soften what the deceitfulness of sin has hardened. Today, while it is still today. Through Christ our Lord. Amen.