For the word of God is living and powerful, and sharper than a two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart. (13) And there is no creature hidden from His sight, but all things are naked and open to the eyes of Him to whom we must give account.
The author of the letter to the Hebrews is unknown. Some Hebrew Christians were seriously thinking of renouncing their faith in Christ and turning back to Judaism but apart from Christ there is no salvation and the only thing that keeps Christians from experiencing God’s rest is unbelief. In our verses it is not the present rest found in Christ in faith being explained but the “rest of God” which is future – the rest of coming glory, an eternal rest which believers enter at Christ’s coming again. Then righteousness will reign and “groaning” creation is delivered and all the promised glory will be accomplished. The perfect complete rest of God is the new heaven and earth, when God dwells among men and sin and death are forever gone – this is God’s rest for His people
It is God’s Word that brings to light and judges the unbelief and workings of the heart. – judges everything in the heart which is not of Him. In this context the Word of God refers to all of God’s spoken revelation, including that which came through His Son, recorded in written form in Scripture. The Word is living since God is the living God. It imparts new life to dead sinners; both the Wordfrom God and the Word about God. It is our only source of knowing specific truth about God and when we see God as He is, we also see ourselves as we are. God’s Word is sharp and piercing and cuts to the very core of our being, the purpose of which is to bring healing, not to leave us wounded. God sees everything – we are naked and helpless before God, not just outwardly but on a heart level.
Man has this deficient historical perspective and the author of Hebrews has the clue to history: Jesus Christ has come and He will come again. In the meantime we wait patiently for God’s rest to come. The Lord God has to cause us to realize through the Spirit that we are lost and cannot get to heaven on the basis of what we do but that salvation is a gift. We have no claim on God whatsoever. We learn in God’s Word that we rest in what Christ Jesus has done. That is the first rest. The second rest discussed here is God’s rest – enjoying all the blessings that God has promised that faithful believers will experience in heaven.