I desire love and not sacrifice, knowledge of God rather than burnt offerings.
God speaks this message through the prophet Hosea. Jesus himself repeats it:
What I want is mercy, not sacrifice.
The word translated here as 'love' or 'mercy' is one of the Bible's most important words. God reveals himself to Moses as
merciful and gracious ... abounding in steadfast love and faithfulness (Ex 34:6).
What God wants from us, therefore, who are made in his image, is that same quality of merciful steadfast love. This alone makes possible the 'knowledge of God' which is more desired by God than burnt offerings. And for this we have been empowered by the Holy Spirit, for
God's love has been poured into our hearts through the Holy Spirit (Rom 5:5).
With that gift there come two commands, as Jesus told the lawyer:
You shall love the Lord your God with all your heart ... You shall love your neighbour as yourself.
And the lawyer in reply said:
You are right, Teacher; [this] is much more than all whole burnt offerings and sacrifices (Mk 12:28-33).
St Paul appeals to his brothers and sisters to offer their bodies as a living sacrifice to God, their spiritual worship (Rom 12:1). By 'bodies', he means their very selves. Our greatest worship is to allow ourselves to be made alive with God's own steadfast love, and so become a living sacrifice, and that requires a whole reorientation of our worldly ways of thinking and acting.
In the first place this worship must consist of a deep love for God, expressed in the proclamation of the mighty acts of his loving kindness. In the second place it must consist of a practical love for one another:
pure religion is this: to care for orphans and widows in their distress, and to keep oneself unstained by the world. (Jas 1:27)
God does not need any of this, so why should it be acceptable to him as worship? It is because it has been made acceptable to him through Jesus Christ. Because he was without sin, Jesus alone was able to offer his Father an acceptable worship:
when Christ came into the world, he said, "Sacrifices and offerings thou hast not desired, but a body hast thou prepared for me." (Heb.10:5)
Jesus offered his body as a living sacrifice to the Father:
Jesus offered up prayers and supplications, with loud cries and tears, to him who was able to save him from death, and he was heard for his godly fear. Although he was a Son, he learned obedience through what he suffered; and being made perfect he became the source of eternal salvation to all who obey him, being designated by God a high priest (5:8-10).
As our high priest he offers the body which God has given him, the body of all those for whom he is the source of salvation, the body of which he is himself the head, the body to which he gives a share in his own life. He
offered for all time a single sacrifice for sins ... For by a single offering he has perfected for all time those who are sanctified (10:12-14).
Since Christ has done this for us, for those who are sanctified in Christ, worship must be this:
Through him, then, let us continually offer a sacrifice of praise to God, that is, the fruit of lips that confess his name. Do not neglect to do good and to share what you have, for such sacrifices are pleasing to God (13:15-16).
Christ united in his sacrifice all the worship and spiritual sacrifices of the future members of his body. He offered not only himself but the whole of redeemed humanity which he had made one body with himself.
In him and through his sacrifice, his members have been made alive in love. Through him, therefore, and his Holy Spirit, they offer back to God all the loving kindness which is his gift to them.
This is the mystery we celebrate in the eucharist. Christ is the true priest of this worship. In the sacrament of this once-for-all event, the body of Christ is offered to the Father by Christ its head and high priest as a living sacrifice, pleasing to God because it is the body of his Son.
With him, in him and through him, the Church itself offers its spiritual sacrifices. Eating his body and drinking his blood, it gives expression to its new being through the sacrament which 'represents' this sacrifice in all its dynamic power.