It is not called baptism, but the ritual of being immersed in water was and still is used in Judaism as a sign of cleansing from religious impurity or being set apart for a particular role
Shortly before Jesus began his ministry, John the Baptist was baptising people by total immersion in the River Jordan in preparation for the coming of the Messiah who would inaugurate the Kingdom of God
John's baptism symbolised for those who were baptised:
their penitence for their sins
God's forgiveness for their sins
a new start in readiness for the Kingdom
Jesus showed his support for John's ministry by coming to be baptised:
When he emerged from the water, he had a vision
This marked the end of Jesus' former way of life as a carpenter and the start of his ministry
John 3:5: 'No one can enter the Kingdom of God unless they are born of water and the Spirit'
Although he may not have baptised people himself, Jesus saw out as a powerful symbol of spiritual rebirth and as a sign of entry into the Kingdom of God
After his resurrection, Jesus instructed his disciples to baptise converts:
Baptism therefore became an important rite of initiation for converts to Christianity- sometimes who households were baptised
Matthew28:19: 'Go and make disciples of all nations, baptising them in the name of the Father and of the Son and of the Holy Spirit'
Rite of initiation= refers to a ceremony that marks become a member of a particular group. Baptism confers membership of the Christian community