Romans 12:1-2
1 I urge you therefore, brethren, by the mercies of God, to present your bodies a living and holy sacrifice, acceptable to God, which is your spiritual service of worship. 2 And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what the will of God is, that which is good and acceptable and perfect.

(all Scripture quotes from NASB)

What does it mean to be a 'holy sacrifice?'

Holy (hagios [40]): set apart, sanctified, consecrated, devoted to the service of God, sharing in His purity and abstaining from earthly defilement; a most holy thing, a saint; sacred, physically pure, morally blameless, and ceremonially consecrated

To be such a living sacrifice, to live in a state of constant devotion to God, in a state that shares His purity, will require us to lean completely upon His mercies. It is by His mercies that Paul urges us to this state. Knowing the vastness of His mercies towards us, we find in ourselves the desire to be so wholly devoted. That desire we find, we find only because in His mercies, He has given us such a desire. In His mercies, He has given us of His Holy Spirit, that we can hope to attain to that desire. So, it is only because of His mercies towards us that we can desire to be a holy sacrifice, and it is only by His mercies towards us that we can be such holy sacrifices.

To be holy is to be devoted. We think of devotion as being a matter of deep commitment. However, the Biblical sense of devotion has more to do with sacrifice. It has to do with those things set apart for God's use. In the OT, you often read of things devoted to destruction. This is not a matter of deep commitment on the part of those things. It is a matter of those things being set apart for God's use, according to His will. They are no longer to be touched by man, taken by man, or used by man. Devotion is, in this sense, the ceremonial consecration.

This is what holiness is about. Being set apart for God's use for God's purposes in the way and in the time that God decides.

What is a 'service of worship?'

Service of worship (latreia [2999]): divine service, sacrificial service; service rendered for hire, ministration, the service of God, the worship of God according to the Levitical code, to perform sacred services; ministration to God

This devotion to His will requires that we be a sacrifice such as Paul has described. Our desires, our rights, and our will must be given up in favor of His will. It is only thus that we can live in righteousness. This is not simply a matter of avoiding sin, nor is it simply a matter of external conformance. Conforming in act, while still rebelling at heart is not devotion, it's the act of a slave. No, both body and soul must be committed to Him. Both body and soul must be presented to Him for active use in His service. It is to be a complete devotion.

No sacrifice was ever acceptable to God from which a portion was held back, and it's no different for us today. If we are keeping any part of ourselves for our own purposes, then we have not given Him all. If we have not given Him all, then we have not really given Him anything. All that we have and all that we are is all that we must give to Him. And, after all, all that we have and all that we are is solely because He gave it to us in the first place. Even delaying, when we know what ought to be our course, is to give Him less than all, for He gave us our times.

Temple, Priest, and Sacrifice: Triune Worship

Matthew Henry writes that "We are temple, priest, and sacrifice." A quick study will show that each of these required sanctification and cleansing. Each of these was required to be kept holy, separated unto God.

The Holy of Holies was for God's use alone. Even the priest was allowed but a single visit in a year. That Holy of Holies, God has now declared to be in you, in me. It remains a place that is to be for His use alone. You and I are to be for His use alone.

The priest, having been cleansed, put on his priestly garments. These were designed to reflect the purity of the God he served, to reflect the majestic rule of the One true God. They were designed to remind both priest and people that God alone is Judge, that He alone would decide among the nations. They were designed to remind both priest and people that the priest himself was a man separated, "Holy unto the Lord." It was written across his very forehead, for all to read and remember. We are now the priesthood. Our lives are our priestly garments. Our lives are to stand as reflections of God's purity and majesty. Our lives are to stand as evidence of His just judgments. Most importantly, our lives are to reflect that fact that we are separated, "Holy unto the Lord." It should be written across EVERY moment of our lives, for all to see and remember.

The sacrifice had to be perfect, free of any defect or disease. To offer God less than your best is unthinkable! In many cases, the animal which was to be sacrificed had been raised specifically for that purpose, carefully cared for and watched over until the day of offering came. Look back across your life. You, too, have been carefully cared for and watched over. I know that I can think back on many instances in my life that should have proven deadly or debilitating. I know several facets of my past that, in my estimation, should have left me too blemished for consideration. But God, in Christ, has chosen to repair those blemishes. God, even in those times when I wanted nothing to do with Him, even when I was His enemy in act and in fact, was watching over the pathways of my life, keeping me from harm, protecting me from myself and protecting me from others, until the day of offering came. He has indeed worked wonders to make sure that I came to that place in proper and acceptable form. Truly, we have been prepared for such a time as this. That's God's providential purpose in action!

This is also the work of the Holy Spirit in us, making certain that we are kept pure and sanctified, so that each day, as we present ourselves at the altar, as we give ourselves in sacrifice, our offering will be acceptable and right.