Whenever, then, you see Christians adoring the Cross, know that they are adoring the Crucified Christ, not the mere wood.* If, indeed, they honoured wood as wood, they would be bound to worship trees of whatever kind, as you, O Israel, worshipped them of old, saying to the tree and to the stone, “Thou art my God and didst bring me forth.” (Jer. 2.27) We do not speak either to the Cross or to the representations of the saints in this way. They are not our gods, but books which lie open and are venerated in churches in order to remind us of God and to lead us to worship Him. He who honours the martyr honours God, to whom the martyr bore testimony. He who worships the apostle of Christ worships Him who sent the apostle. He who falls at the feet of Christ’s mother most certainly shows honour to her Son.
St. John Damascene
Apology Against Those Who Decry Holy Images
Quoted from Leo of Neapolis, Against the Jews