Mass as Sacrifice
The eurcharist is a true sacrifice for Jesus Christ. The Eucharist is performed at every catholic mass. Poiein is translated as offer this or sacrifice this, this word is used both in the old and new testaments used for the sacrifice.
Community and Liturgy
Liturgy is a binding principle of society. The community makes up the liturgy by participating in a parish, church activities, family, praying, friends etc. Liturgy can't work without the community and the community wouldn't be growing without the liturgy.
Liturgical Diversity In The Church
There is diversity within the liturgy of the church because everyone is unique. Everyone prays differently, does different actions to show they're faithful to the church, do different things to participate in the community etc. Diverse traditions, culture, leadership, beliefs etc. all make up the liturgical diversity in the church.