How can burning flesh be a sweet-smelling aroma to God?
My dear friend, to answer your question, I believe that we must understand that God is Spirit (John 4:24), and as such, not limited to human, physical capacities such as the sense of smell. The use of a descriptor such as “a sweet savor” to God is more a figure of speech, a metaphor if you will, relating God’s satisfaction in the obedience of His people in seeking His forgiveness rather than the actual aroma of the burning flesh of an animal sacrifice. Additionally, it helps to remember that the OT sin offerings described in Leviticus are types of Christ Jesus in His sacrificial death for sinners on Calvary’s cross (see Hebrews 9, especially verses 7-13). There is a nice summary of the main points of the OT sacrifices in the Morrish Bible Dictionary under the heading of offerings: “…But even in the sin offering the fat was burnt on the brazen altar, and it is once said to be for a sweet savour (Lev. 4: 31), thus forming a link with the burnt offering. The sweet-savour offerings represent Christ’s perfect offering of Himself to God, rather than the laying of sins on the substitute by Jehovah.”
Thus, burning the fat of the animal sacrifice was not a sweet savor in the sense that God enjoyed the actual aroma of the burning tissue, but rather it, I believe, refers to God’s satisfaction in the sacrifice of Christ Jesus on the sinner’s behalf (consider 2 Corinthians 5:21; 1 John 4:10). I also believe that it pleases God to see a penitent sinner seeking the forgiveness of God for sins committed by a sincere and contrite heart. In supporting this thought, we might consider Psalms 51:16-17 where we read: “For Thou desirest not sacrifice; else would I give it: Thou delightest not in burnt offering. The sacrifices of God are a broken spirit: a broken and a contrite heart, O God, Thou wilt not despise.” Thus, it is, I believe, the penitent heart which seeks for grace in forgiveness which God takes pleasure in, and not the actual aroma of a burnt offering which the human would smell. God is spirit, and what pleases Him is the sacrifice of a broken and contrite heart in a sinner who turns in faith for mercy and forgiveness to the propitiatory work of the Lord Jesus Christ on Calvary’s cross.
In the New Testament, we also can find this metaphoric use of the phrase “a sweet savor to God”. In 2 Corinthians 2:15, we read, “For we are unto God a sweet savour of Christ, in them that are saved, and in them that perish….” William MacDonald in his Bible Commentary on 2 Corinthians 2:15 says: “…F. B. Meyer states it well: ‘When, therefore, we are told that we may be to God a sweet savour of Christ, it must be meant that we may so live as to recall to the mind of God what Jesus was in His mortal career. It is as though, as God watches us from day to day, He should see Jesus in us, and be reminded (speaking after the manner of men) of that blessed life which was offered as an offering and a sacrifice to God for a sweet-smelling savour.’” (SF) (644.2)