The atonement is the basis of our hope. God wants us to keep belief in the atonement renewed in our minds continually. We may do this by private meditation at any time at any place. The Lord's Supper employs symbolic materials which can be touched and tasted to give more substance to our faith. Paul used the cross as a symbolic reminder of the atonement.
Christian art uses many symbols constructively.
Art was used in the Tabernacle and Temple. Symbolic art and venerated images are not to be confused with each other. God sees us in our earthly surroundings and uses some of these earthly things to make our faith more concrete. We are social beings also, and God uses the physical presence of others to reinforce our faith.