Hebrews 4 is all about rest in Christ, but that rest is not found in merely knowing about God's salvation. It is in not rejecting the gift of faith that receives all the essential nourishment in His sacrifice for us. According to the writer to the Hebrews, the ancient people of God, while in the wilderness following their miraculous escape from Egypt by God's mighty hand, rejected God, His gifts and did not enter the rest He had given them. They had other gods, mostly their own stubbornness and unbelief. It is a long chapter, but worth the read. Read also Psalm 95 to hear references to this rejection and loss of rest in the peace of God. They did not enter the promised land but their children did. Joshua, Moses' protégé and leader chosen by God, is the first Joshua, or "Savior" as his name translates. Jesus is the second Joshua, as His name is the Greek name for Joshua and therefore, He is our Savior, who brings us through the wilderness of life to the promised land of a new heaven and earth.
14 Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession. 15 For we do not have a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sin. 16 Let us then with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need.
Jesus is our Sabbath rest, the focus of our gathering to receive gifts through faith. We dare not reject these gifts because they bring life to us from His death on the cross. His suffering in our place was to atone for our sinfulness and sinning. We, too, are on a wilderness walk, but not to our condemnation. Through trusting and relying on our Lord, we become more convinced of our salvation through Jesus' work--in fact, He had no rest so that we could have complete rest and trust in Him alone for our salvation. Through His Word and His mysteries, the Sacraments, we are renewed and convinced of our salvation, both daily through our Baptisms, and when we gather for worship of God when we set aside time for the Lord to give us gifts through His service to us.
I come, O Savior, to Thy Table,
For weak and weary is my soul;
Thou, Bread of Life, alone art able
To satisfy and make me whole:
Lord, may Thy body and Thy blood
Be for my soul the highest good! (The Lutheran Hymnal 315:1)