Sometimes, we use objects as symbols to help us focus our prayer.
For example, once a year (on Palm Sunday) many Catholic churches bring palm-branches into the Church. This reminds us that palms were laid out to honour Jesus when he entered Jerusalem. The palm-branches help us focus on the day's prayers and celebration of Jesus Christ as our Lord and Saviour.
While we know that no image or 'thing' can capture the presence of God, which is a mystery beyond our comprehension, we also recognise that as human beings we need to express our faith in a human way.
In becoming human in the person of Jesus, God has shown us that created realities are not to be scorned but embraced as part of our loving response to God. When we portray mysteries of our faith through human realities we are not 'confining' God but making a statement about what we hold dear.