The symbols in the Church building.
The Lamb of God.
The next day he saw Jesus coming toward him, and said, “Behold, the Lamb of God, who takes away the sin of the world! John 1:29
The Culmination of sacrifices in the Old Testament was accomplished when God offered up His own Son as the sacrifice for the sins of all mankind. Sacrifice for sin has now been ended in Christ Jesus, the Lamb of God.
Baptism
Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, Matthew 28:19
The Christian symbol for the sacrament of Holy Baptism is the scallop shell. The three drops of water are a reminder of our new relationship with the Triune God, and the baptismal graces of forgiveness of sins, life, and salvation.