People are often scared to think about the "two covenants" (the Old and the New)

People are often scared to think about the "two covenants" (the Old and the New), for fear that it's a theological puzzle beyond their understanding.

In truth, it's the simplest problem in the Bible to grasp: the New Covenant is the promises of God to Abraham and to his descendants by faith (that means you if you believe John 3:16)--that He will bless you abundantly now and forever. That's the New Covenant (you can read the seven promises in Genesis 12:2, 3). In contrast, the Old Covenant is the promise of the people at Mt. Sinai to "do" everything that that they think God requires (Ex. 19:8).

Under the Old Covenant we see the Ten Commandments as ten stern demands. But under the New, we see them as ten glorious promises that the Lord will save us from the sin mentioned there. For example, the seventh: under the Old Covenant it's a stern demand that we never covet our neighbor's spouse, never look on someone lustfully, etc.

But under the New Covenant, it's a promise that the Lord will hold us by the hand forever and save us from falling into that hole (the wrong woman, or man) that Proverbs 22:14 says is a "deep pit." The wonderful promise applies to us in our teenage years, also. (That's when it's especially precious.)

But is there no condition regarding what we must do?

Yes: we must believe the Preamble to the Ten Commandments. We must believe that by virtue of His sacrifice of Himself on His cross, the Lord Jesus has delivered us "out of the land of Egypt, out of the house of bondage." By becoming our new Head of the human race, our new Adam, Christ has adopted the human race in Himself (Eph. 1:3-7); He has become the "Savior of the world" (John 4:42--that is, in a legal or judicial sense), but "especially" so of "those who believe" (1 Tim. 4:10). That's the practical. His love (agape) constrains us to live joyfully unto Him; self-sacrifice for Him is a joy.

That's the truth of the Preamble to the Ten Commandments. You must believe it. Choose to. You believe; let Him "help [your] unbelief" (He will! Mark 9:24).