Keep yourselves in the love of God, looking for the mercy of our Lord Jesus Christ unto eternal life.
Saint Jude, also known as Saint Thaddeus was one of the twelve apostles. His name is Ὶούδας in the koine Greek which is a translation of the Hebrew name Y'hudah. He is known in both the King James version and Douay-Rheims versions as the brother of Saint James, further being linked in the Epistle of Jude who the author identifies himself as "Jude, the servant of Jesus Christ and brother of James".
In the lists of the Apostles in Matthew and Mark (10:3, 3:18 respectively) Saint Jude is not listed but a Saint Thaddeus is. Early Christians linked the two lists by positing a "Jude Thaddeus". Thaddeus also seems to be a nickname for Saint Jude and many of the apostles have several names (For example, Simon//Peter).
At the last Supper we find that Saint Jude askes Jesus (John 14:22): Judas (not Iscariot) said to Him, “Lord, how is it that You will manifest Yourself to us, and not to the world?”
One tradition holds that Saint Jude retrieved Jesus's burial cloth that he used to heal a king in Edessa. In 37 AD, he travelled to Mesopotamia (current day Iraq) and aided in the Church of the East, a church founded by Saint Thomas. He also travelled in Libya, Turkey, and Persia with Saint Simon. He wrote his epistle to the newly converted Christians in the Eastern Church around the year 60 AD warning them to be careful of false teachers and to stand firm in their faith. His Epistle contains some of the finest expressions of praise to God in the New Testament and urges the Christians there to do the impossible - to stay in God's love, mercy and truth even under such severe persecutions.
He and Saint Bartholomew are traditionally held to be the first to bring the Gospel and Christianity to Armenia and both are venerated as the patron saints of the Armenian Apostolic Church.
Saint Jude suffered martyrdom along side Saint Simon the Zealot around 65 AD in Beirut. He was beheaded with an axe and is therefore often represented in art work with one. He is also often depicted with a flame over his head, representing his receiving of the Holy Spirit at Pentacost.