We Orthodox make use of the word "sacrifice" a lot in our prayers and Liturgies and we use it both as a noun and verb. Many non-Orthodox see the use of this word and decry it for the use of that word, to them, suggests that we are doing it to "get right with God" and thus nullify God's grace. If the sacrifice of praise we offer to the Lord were propitiatory, such a criticism would be right on. However, the sacrifice of praise that forms the core of Eastern Rite Liturgies and prayers is expiatory. There is a difference. Expiatory sacrifice is directed towards us, towards changing us because our sinfulness makes perfect worship, like what goes on in the Heavens, impossible. Propitiatory sacrifice, on the other hand, is meant to assuage God's wrath by some sort of appeasement. The latter definitely is a "theology of works" which is rightly decried as something lacking God's grace. To make the distinction even clearer, reference this little snippet from St. Anthony the Great.
God is good, dispassionate and immutable. Now someone who thinks it reasonable and true to affirm that God does not change, may well ask how, in that case, it is possible to speak of God as rejoicing over those who are good and showing mercy to those who honor Him, while turning away from the wicked and being angry with sinners. To this it must be answered that God neither rejoices nor grows angry, for to rejoice and to be offended are passions; nor is He won over by the gifts of those who honor Him, for that would mean He is swayed by pleasure. It is not right to imagine that God feels pleasure or displeasure in a human way. He is good, and He only bestows blessing and never does harm, remaining always the same. We men, on the other hand, if we remain good through resembling God, are united to Him; but if we become evil through not resembling God, we are separated from Him. By living in holiness we cleave to God; but by becoming wicked we make Him our enemy. it is not that He grows angry with us in an arbitrary way, but it is our own sins that prevent God from shining within us, and expose us to demons who punish us. And if through prayer and acts of compassion we gain release from our sins, this does not mean that we have won God over and made Him change, but that through our actions and our turning to God, we have cured our wickedness and so once more have enjoyment of God's goodness. Thus to say that God turns away from the wicked is like saying that the sun hides itself from the blind.--St. Anthony the Great, "On the Character of Men" from the Philokalia.