Speaking in tongues refers to the Christian belief that a person can be given the ability by the Holy Spirit to speak in a language unknown to them. The origins of this belief can be found in the New Testament.
In Acts 2 the disciples of Jesus were gathered in Jerusalem during the Jewish festival of Pentecost.
The disciples were together in one room. Suddenly a sound like a violent wind was heard and tongues of fire came down and rested on the disciples. Wind and fire are Old Testament symbols for the presence of God. For example, God appeared to Moses in the burning bush and God’s presence was like a wind in the book of Ezekiel.
After this experience the disciples were suddenly able to communicate in different languages, none of which they had previously known. This is referred to as speaking in tongues.
Some believe that speaking in tongues is the ability to speak in human languages for the purpose of telling the message of Jesus. This is supported by the account in Acts where those visiting Jerusalem could hear the disciples speaking in all different human languages.
Others believe that speaking in tongues refers to some kind of spiritual or heavenly language. This is supported by Paul writing in 1 Corinthians where he refers to speaking in the tongues of angels.
Today some Protestant churches believe that speaking in tongues is still a gift from the Holy Spirit. However, other Protestant churches reject this idea, believing the gift of tongues was only for the time of the early Church.