Paul provides an illustration to show how the Christian is no longer bound by the law, but instead is free from that bondage and is now bound to Christ and is free to live for Him.
The Old and New Union (v1-4):
Death breaks the binding power of the law (v1-2)
Death provides freedom for a new union (v3-4)
The Old and New Life (v5-6):
This new life brings death to the old self (v5)
This new life releases us from the bondage of the law (v6a)
This new life creates freedom to serve God (v6b)