The Meaning of a Key or Keys in Western Painting

The Spiritual Significance and Meaning of Keys in  Byzantine, Gothic and Renaissance Painting

From the earliest period of Christian history the church fathers realized the value of religious images in helping to keep sinners on the road to salvation.  The Church commissioned artisans and craftspeople to create religious imagery for churches and state building. These sacred images acted as moral instruction and spiritual comfort to uneducated peasants. The divine artworks served as a constant reminder of the hellish tortures that awaited backsliders and sinners if they strayed from Gods word and church law.

Key on a pillow-  symbolizes marital faith.

Figure holding a key - signifies holy, divine, sacred personage; represents  the sanctified authority of the papacy and the Church's power to admit people into heaven.

Key in a lock- symbolizes acceptance of Jesus Christ and  eternal salvation,  immortality. "I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven; and whatsoever thou shalt loose on earth shall be loosed in heaven." --  Matthew 16:19

Key lying beside a lock - symbol of free will