Paul wrote Galatians to explain this.
He uses the example of tutor for law to guide the kid until he is a mature son.
I will like to use the following modern days artifacts to explain Law and Grace.
- Law is the scaffolding of a building during its construction. When the concrete has settled and matured, the building is strong and can stands on its own. The scaffolding is not longer needed and is taken down.
- Law is like the support wheels of children bicycle. When the child know how to ride with 2 wheels, the support wheels are more hindrance and help and they are taken off.
- The Law is meant to lead us to Grace by point out our sins and our inability to live up to its demand.
(Gal 3:24 So the law was put in charge to lead us to Christ that we might be justified by faith.)
- Once we received and internalized grace, we need not the law, not because we are freed to break the laws but that in grace, we will walk only in righteousness naturally.
(Gal 5:18 But if ye be led of the Spirit, ye are not under the law." See the fruit of the Spirit in 5:22-23 which surpass the Laws)
- He who loves automatically fulfill the commandments.
(Rom 13:8b for he who loves his fellowman has fulfilled the law).