Quoting from Pastor Bill Cwirla's article "The Law and the Gospel in the Liturgy":
The Liturgy runs in both a "sacramental" and a "sacrificial" direction. God justifies man sacramentally, and justified man serves God sacrificially. God speaks his Word and as his Word has its mortifying and vivifying way with us, we speak to God and to one another. God opens our lips, and our mouths declare his praise (Ps 51:15).
Jesus Christ always remains the center and focus in the liturgy, whether we are speaking sacramentally or sacrificially. Through Jesus Christ, the Father bestows forgiveness, life, and salvation by the Holy Spirit who works through the Word. And through the same Jesus Christ, the church renders her thanks and praise sacrificially to the Father in the Holy Spirit. In both directions, Jesus Christ is the mediator between God and man (1 Tim 2:5).
Where sacrament and sacrifice are confused, there will be a corresponding confusion of the Law and the Gospel. Worship that is focused on our prayer, praise, good works, love, caring, outreach, mission, stewardship, and sanctification instead of on Christ's saving death and resurrection, is focused on the Law and not the Gospel. Sacrifice without sacrament is Law without Gospel. To worship God according to the Law is idolatry, even if the God whom we are worshiping is the one, true God.
This distinction of sacrament and sacrifice provides a Christocentric litmus test for worship. If what is said, sung, or preached in the liturgy could be said, sung, or preached had Jesus Christ never died on the cross and rose from the dead for the salvation of the world, then that worship is not uniquely Christian. The sacrificial death of Jesus for the life of the world is the essential, core of the Liturgy. "For as often as you eat of this bread and drink of this cup you proclaim the Lord's death until he comes" (1 Cor 11:26).