There are two things to remember about Paul in the study of such a subject.
First: He was a Jew and he knew all about offerings. Sacrifices were not forms to him and a living sacrifice was not a meaningless expression. He had been present on the great day of Atonement when the scapegoat bore away the sins of the people. He had heard the chimes of the bells on the high priest's robe as he moved to and fro before the entrance to the holy of holies, and he had waited with breathless silence for him to come forth giving evidence in his coming of the fact that Israel could once more approach Jehovah. The text to him was throbbing with holy memories and was full of significance.
Second: He received his instructions concerning these things of God, not from men, for when he writes to the Galatians he says: "But I certify you, brethren, that the gospel which was preached of me is not after man, for I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ" (Galatians 1:11-12). And so, since he is a heaven-taught man, we must listen while he speaks and give heed to his entreaties.
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The context. We shall not appreciate this striking text unless we take into account its setting.
The first chapters of Romans present to us a black cloud indeed, for when the first sentences are spoken we shudder because of their intensity. We read in the twenty-fourth verse that God gave the people up to uncleanness; in the twenty-sixth verse that he gave them up to vile affections, but in the twenty-eighth verse that he gave them over to a reprobate mind. With this awful condition of affairs we start; and yet for fear that the man who counts himself a moralist might read these verses and feel that they did not apply to him, Paul writes in the third chapter and the twenty-second verse these words, "Even the righteousness of God, which is by faith of Jesus Christ, unto all and upon all them that believe; for there is no difference." But when the cloud is the blackest the rays of light begin to appear, and they are rays of light from heaven; looking on the one side at mystery and catching a vision on the other side of grace, Paul exclaims, "I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service" (Romans 12:1).
The word mercy is of frequent occurrence in the Bible. "From everlasting to everlasting is God's mercy," we read. This gives us some idea of duration. "New every morning and fresh every evening are his mercies." This reveals to us the fact that they are unchanging. "He is a God of mercy." This is his character. "Let the wicked forsake his way and the unrighteous man his thoughts and let him return unto the Lord and he will have mercy upon him." This is the invitation of God given to all the world! But Paul is not speaking of mercy in general; he goes on in his masterful argument outlining the doctrines of grace and on the strength of that he uses the text.
First: We are justified. The fifth chapter and the first verse, "Therefore being justified by faith, we have peace with God through our Lord Jesus Christ." In justification our sins are pardoned and we are accepted as righteous because of the righteousness of Christ, which is imputed unto us and received by faith alone. And yet to him this definition in every day language means that, being justified, we stand before God as if we never had sinned. No wonder that in the light of such a doctrine Paul could say, "I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service" (Romans 12:1).
Second: We are kept safe. Romans 5:10, "For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life." Literally the closing part of this verse is, "We are kept safe in his life." A child in its mother's arms could not be so secure as we in his life. Underneath us are the everlasting arms and around about us the sure mercies of God.
Third: We are baptized into his death. "Know ye not that so many of us as were baptized into Jesus Christ were baptized into his death?" (Romans 6:3). "The wages of sin is death." This is God's irrevocable statement, but Christ died for our sins and Paul's argument here is that we died with him, so the demands of the law have been met and we are to go free. No wonder Paul could say, "I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service."