Christian symbols have been used for thousands of years.
A list of links to many symbols. Some familiar, some less so.
Sacramentals are sacred signs and rituals sometimes accompained by a prayer. Sacramentals are such things as the Sign of the Cross, Holy Water, Scapulars, Holy Medals, and Symbolic gestures such as kneeling and blessing, and Sacred Signs such as fire, candles and ashes.
What is a Sacramental? – All that Catholic Stuff (3.33 mins)
The seven sacraments of the Catholic Church are community celebrations of our belonging to the Body of Christ.
Recognising Signs of God