Certain objects, images and actions carry Christian symbolism and have an inner meaning that reflects the ideas of Christianity. Many of the symbols come from various parts of the world and are known to many cultures.
An early symbol of Christianity is the Ichthys, which is the shape of a fish. Tomb paintings have also given evidence to some early symbols such as the dove, which symbolizes the Holy Spirit, the lamb, which is symbolic of sacrifice, and so on.
The Christian cross is one of the most significant and widely recognized symbols. It is the representation of the crucifixion of Jesus. The Bronze Age marked the beginning of the precise representation of the cross, but it wasn't until later on that it became the dominant sign of Christianity. The cross is supposed to remind one of the sacrifice of Jesus Christ to save his people and conquer death. There are many forms and variations of the cross and one can find this symbol on altars, in processions, and being used by priests to bestow blessings.
Early Christian tomb paintings introduced the use of icons, which are images or representations of symbolic meaning. Christianity experienced years of opposition to icons, which was called the Iconoclastic Period. Opposition to images that represent the religion was supported by the idea that veneration of images is considered idolatry. Today, icons continue to exist and are primarily used in the Eastern Orthodox, Eastern Catholic and Oriental Orthodox Churches.