In contemporary Christianity, the cross is a symbol of the atonement and reminds Christians of God's love in sacrificing His own Son for humanity. It represents Jesus' victory over sin and death since it is believed that through His death and resurrection He conquered death itself.
"Having disarmed the powers and authorities, He made a public spectacle of them, triumphing over them by the cross." (Colossians 2:15).
The Catholic Church celebrates the feast of the Triumph of the Cross under the same name In Exaltatione Sanctae Crucis on September 14th. What is the meaning of the cross?
Simply put, the meaning of the cross is death. The cross was an instrument of execution that resulted in death by the most tortuous and painful of ways. In crucifixion a person was either tied or nailed to a wooden cross and left to hang until dead. Death would be slow and excruciatingly painful; in fact, the word excruciating literally means "out of crucifying." However, because of Christ and His death on the cross, the meaning of the cross today is completely different.
In Christianity, the cross is the intersection of God's love and His justice. Jesus Christ is the Lamb of God who takes away the sin of the world (John 1:29). The reference to Jesus as the Lamb of God points back to the instruction of the Jewish Passover in Exodus 12. The Israelites were commanded to sacrifice an unblemished lamb and smear the blood of that lamb on the doorpost of their homes. The blood would be the sign for the Angel of Death to pass over that house, leaving those covered by blood in safety. When Jesus came to John to be baptized, John recognized Him and cried, "Behold, the Lamb of God, who takes away the sin of the world!" (John 1:29), thereby identifying Him and God's plan for Him to be sacrificed for sin.