“The Holy Spirit also testifies to us about this. First he says: “This is the covenant I will make with them after that time, says the Lord. I will put my laws in their hearts, and I will write them on their minds.” Then he adds: “Their sins and lawless acts I will remember no more.” And where these have been forgiven, there is no longer any sacrifice for sin” ( Hebrews 10:15-18 )
The Holy Spirit does so many things in our lives but one of His most important roles is to testify and confirm the New Covenant to us. It is His job to reassure and remind us of what was promised. The Covenant we enjoy is vastly superior to the old one and was extremely costly for God to bring it to pass. Therefore He has made it the job of the Holy Spirit to constantly remind believers of the amazing things that are included.
The Covenant enjoyed through Jesus was prophesied through the prophet Jeremiah hundreds of years before Christ ( Jeremiah 31:31-34 ). It includes many things and in these verses we are reminded of that to which the Holy Spirit is set to testify. First, God writes His laws in our minds and upon our hearts. God’s laws are now a part of us, not something external to accuse us, but they are written by the Spirit of God on the inside of us so fulfillment comes naturally by walking after the Spirit ( Romans 8:4, Galatians 5:16 ). Secondly, God will not only forgive our sins but He will not remember them. God completely and permanently dealt with sin once for all through Jesus’ sacrificial death on the cross ( Hebrews 9:28, 10:10, 10:14, 10:18, I Peter 3:18, I John 2:2 ). Because of it, by faith, we have been made holy and acceptable to God which is why God sends the Holy Spirit to confirm this to us, He doesn't want us to miss this amazing truth!
To use an old metaphor; the Holy Spirit is really the icing on the entire redemption cake! Not only are we saved, redeemed and restored through Jesus’ precious blood, but the Holy Spirit constantly speaks these things to us so that we will have confidence in our relationship with God ( Hebrews 10:22 ). Jesus foretold that this would be His function, “But the Counselor, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you” ( John 14:26 ). The Amplified Bible calls Him the Comforter, Counselor, Helper, Intercessor, Advocate, Strengthener and Standby. All are marvelous words to describe how He relates to us.
God thought that is was imperative that we be constantly reminded of our Covenant because the reason Jesus died was to bring it to pass. This is good news for us because it means we can find peace and rest through Jesus by confirmation of the Holy Spirit speaking these things to us, “This then is how we know that we belong to the truth, and how we set our hearts at rest in his presence whenever our hearts condemn us. For God is greater than our hearts, and he knows everything. Dear friends, if our hearts do not condemn us, we have confidence before God” ( I John 3:19-21 ).