A covenant is more than an agreement. It's a certainty bound by blood, one which cannot be broken, but on pain of death.
Jesus cut a new covenant with the entire human race when He died on the Cross.
He announced this New Covenant at the Passover meal just before His Crucifixion:
"For this is my blood of the new testament, which is shed for many for the remission of sins."
(Matthew 26: 28)
This New Testament, this New Covenant, is announced in Jeremiah and Ezekiel, yet repeated in the Book of Hebrews:
"10For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
11And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
12For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more." (Hebrews 8: 10-12)
Now, Jonathan and David cut a covenant, in which Jonathan exchanged his robe, his sword, and his girdle. In a similar manner, Jesus exchanges with us His standing, His power, and his resources. As Christ is, so are we in this world (1 John 4: 17). Our enemies become Jesus' enemies. Our needs become His needs, and we can thus rest that no matter what challenge we face, Jesus is there to see us through and grant us victory to overcome, for in Christ Jesus we are more than conquerors (Romans 8: 27)
The New Covenant is much more than the forgiveness of sins, but this reconciliation enacts the entire covenant for us. When we believe on Jesus, that He died for our sins and was raised for our justification, we allow God the Father to write His laws in our minds and our on our hearts. He becomes a God to us, meeting every need, and He causes us to know Him intimately.
Jesus is your Jonathan, and as "The Gift of God" to the world (John 3: 16), you can receive Him and enter into the New Covenant with God your Father (John 20: 17)