in God's economy, there is the age of law and the age of grace. right now we are in the age of grace, because God in Christ has come to us to be grace to us. like John 1:17 said "grace and reality came through Jesus Christ". but we need to know why there is the age of law, if the original intention of God is to be grace to us.
like the apostle Paul mentioned, law was added about 400 years later. the fact that the law was added shows us that law is not the original intention of God. but the law was added because of the transgression of the people. furthermore, there is also some other reason for necesariness of the law. this is also mentioned by the apostle Paul, who referred to the law as the child conductor, the custodian of God's people.
we need to come to see the covenants God made with His people. in Genesis, God made a covenant with Abraham, which was according to God's original intention. but then in Exodus, on Mount Sinai, God made another covenant through Moses with His people, by giving the law. This was referred to in the book of Hebrews as the first covenant. then Jeremiah chapter 31 told us about the new covenant, which is mentioned by Paul in Hebrew as the better covenant.
the purpose of God giving the law is, on the positive side, that He would give the law as a portrait of Himself, to show His people what kind of God He is. for example, God is love, God is full of compassions, and God is light, etc. so through the law, we can understand the virtues of our God. also, on the negative side, God wants to expose man his poor and sinful condition that man in themselves can never reach and fulfill God's requirements. Also, through the law, sin, sins, and tresgressions can be manifest. God shut all His people under the custody of law, until Christ comes as grace, and then the law can lead us to Christ, who is grace.
Christ, as the embodiment of the Triune God, is grace to us. but in order for Him to be grace to us, there has to be process for Him to pass. John 1:1 tells us that in the beginning was the Word. then in John 1:14, this Word became flesh and tabernacled among us. God the Father, embodied in the Son, became a man, Jesus. Jesus went through human livings for 33 and a half years. After death and resurrection, 1 Corinthians 15:45 tells us that He became the life-giving Spirit, which means He now is able to breathe Himself into the disciples, as He did in John 20. now this One is our bread of life, living water of life, and also our breath of life. eating, drinking and breathing are the three basic and crucial matter for us human being to exist. in the same principle, for our spiritual living, we also need to eat the bread of life, to drink the living water of life, and to breathe in the breath of life. for our Christian life, we need to experience and enjoy Christ as our grace, our life and life supply.
as the believers, we all experience Christ as grace individually, but our individual experience is for the corporate Body of Christ, as the organism of the Triune God, which will ultimately consummate as the New Jerusalem, the holy city of God, the masterpiece of God.