Why is physical matter used in Church Sacraments?
Q671 · The Holy Sacraments
In the world, these sacraments are fulfilled by God’s word and prayer, along with the use of physical substances: water in the baptism; holy oil in chrismation, bread and wine in the Eucharist. However, in heaven, we do not need matter to be united with God, since our flesh which was sown in corruption will be raised without corruption. God who created humanity with a body and soul does not despise matter but sanctifies it. Through the sacraments, God honors matter and the Holy Spirit uses what is seen, to deliver the unseen blessing. The Word became visible flesh, a true human. In the transfiguration, He sanctified His clothes so that they became white as the light (Matt. 17:2). In the sacraments, the physical object is like a banknote. Even though it is just a piece of paper (or plastic), its value is derived from the code or number that it carries and the fact that someone of authority issued it.