Actually, we do talk about Christ's sacrifice in a great number of booklets, articles, lessons, sermons, etc. "Jesus Christ is the focal point of Christianity," says the Fundamental Beliefs booklet (page 14). Perhaps the misperception comes from the fact that most today have heard about Jesus as Savior, but many have not really heard His message. His message shows what His sacrifice means for us personally (repentance and striving to do what He said—Acts 2:38; Matthew 7:21; Luke 6:46) and for the world (John 3:16; Hebrews 2:10). Thus we strive to fill in the missing pieces of the plan of salvation.
Jesus Christ is central to the entire plan. We see Jesus Christ in all seven of God's festivals—all seven major steps in God's plan (see God's Holy Day Plan: The Promise of Hope for All Mankind). The first one, Passover, represents the sacrifice of Jesus Christ, which is also in the UCG Constitution as a fundamental belief. It is stated this way:
"We believe God so loved the world of helpless sinners that He gave His only begotten Son, who, though in all points tempted as we are, lived without sin in the human flesh. That Son, Jesus Christ, died as a sacrifice for the sins of humanity. His life, because He is the creator of all humanity, is of greater value than the sum total of all human life. His death is, therefore, sufficient to pay the penalty for every human being's sins. In paying this penalty He has made it possible, according to God's plan for each person and for humanity as a whole, to have their sins forgiven and to be released from the death penalty (Hebrews 4:15; 9:15; 10:12; John 1:18; 3:16; Colossians 1:16-17, 22; 1 John 2:2; 4:10; Ephesians 1:11; Revelation 13:8)."
"He died a hideous death, as our Passover, that we might understand the magnitude of sin and the monumental significance of His sacrifice, which was made for every human being" Fundamental Beliefs, page 15). Through the awesome, loving sacrifice of Christ we can be reconciled to the Father, developing a relationship that will last forever.
For More Information: Fundamental Beliefs, God's Holy Day Plan.