A fragrant offering

The sacrifices of the Old Testament were meant to be a sweet aroma to the Lord (Leviticus 1:9, 2:2, 3:5).  Likewise in the New Testament we see that when we walk with the Lord our lives become a fragrant aroma. 

But thanks be to God, who always leads us in triumph in Christ, and manifests through us the sweet aroma of the knowledge of Him in every place. For we are a fragrance of Christ to God among those who are being saved and among those who are perishing; to the one an aroma from death to death, to the other an aroma from life to life. And who is adequate for these things? - 2 Corinthians 2: 14-16

The reason we are to live lives of holiness is because God is holy, because Christ lived a perfect life and we are to imitate Him, and because the world needs to see Christ in us through love and conduct. 

Therefore be imitators of God, as beloved children; and walk in love, just as Christ also loved you and gave Himself up for us, an offering and a sacrifice to God as a fragrant aroma.  

But immorality or any impurity or greed must not even be named among you, as is proper among saints; and there must be no filthiness and silly talk, or coarse jesting, which are not fitting, but rather giving of thanks. For this you know with certainty, that no immoral or impure person or covetous man, who is an idolater, has an inheritance in the kingdom of Christ and God.    - Ephesians 5:1-5

We could rightly ask "What true son doesn't want to please his father?"  When we act as rebellious sons we become odious not only to God but to the world as well.  We are sinners saved by grace, but we are so much more!  We are called to be representatives of Christ, to live out the newness of life that has been given to us.  If we excuse sin and refuse to grow in holiness we are denying our calling and rebelling against God's work in our lives.