It takes true growth, and maturity to understand this.
It wasn’t until the crucifixion that the new covenant took effect. Thus, while Jesus walked this earth the old covenant was still in force.
Paul very much distinguishes between the “ministry of death, carved in letters on stone,” as that which once had glory, and the “ministry of the Spirit,” which surpasses it in glory (2 Corinthians 3). His point being that while Christians are not bound by the letter of the law, God has written on their hearts. The Spirit will guide, and restrain. They will no longer do what is “required” of them, but will act in accordance with their new nature (Romans 2.12–16).
It wasn’t until the crucifixion that the new covenant took effect. Thus, while Jesus walked this earth the old covenant was still in force.
“For if the blood of goats and bulls, and the sprinkling of defiled persons with the ashes of a heifer, sanctify for the purification of the flesh, how much more will the blood of Christ, who through the eternal Spirit offered himself without blemish to God, purify our conscience from dead works to serve the living God.
Therefore he is the mediator of a new covenant, so that those who are called may receive the promised eternal inheritance, since a death has occurred that redeems them from the transgressions committed under the first covenant.
For where a will is involved, the death of the one who made it must be established. For a will takes effect only at death, since it is not in force as long as the one who made it is alive. Therefore not even the first covenant was inaugurated without blood.” (Hebrews 9.13–17)
Therefore he is the mediator of a new covenant, so that those who are called may receive the promised eternal inheritance, since a death has occurred that redeems them from the transgressions committed under the first covenant.
For where a will is involved, the death of the one who made it must be established. For a will takes effect only at death, since it is not in force as long as the one who made it is alive. Therefore not even the first covenant was inaugurated without blood.” (Hebrews 9.13–17)
Paul very much distinguishes between the “ministry of death, carved in letters on stone,” as that which once had glory, and the “ministry of the Spirit,” which surpasses it in glory (2 Corinthians 3). His point being that while Christians are not bound by the letter of the law, God has written on their hearts. The Spirit will guide, and restrain. They will no longer do what is “required” of them, but will act in accordance with their new nature (Romans 2.12–16).