The original gesture of Christian prayer was spreading the arms and hands heavenward.
There is no mention anywhere in the Bible of joining hands in prayer, and that custom didn’t surface in the church until the ninth century.
In Roman times, a man would place his hands together as an offer of submission that meant, “I surrender, here are my hands ready to be bound or shackled.”
Christianity accepted the gesture as a symbol of offering total obedience, or submission, to God.
That’s why Christians put their hands together when praying.