They were Apostles of Our Lord and were brothers. We are let known what eager and ardent apostles of the Faith Saint Simon and Saint Jude were, first by the distance they traveled to preach the Gospel (they went eventually as far as Persia), and also by the names given to them. Saint Simon is called the Zealot, both to distinguish him from Simon Peter and to show his ardor in preaching the true Faith. Saint Jude is called Thaddeus, which means big-heart.
Saint Simon was martyred by being crucified. Saint Jude was martyred by being clubbed to death. Both were killed in the same year. Their relics were brought back and were placed near those of Saint Peter and Saint Paul in the Vatican, in Rome. Saint Jude is the author of one of the Epistles in the New Testament. “Keep yourselves in the love of God, waiting for the mercy of Our Lord Jesus Christ unto life everlasting,” Saint Jude writes in his holy Epistle.
See also: Saint Simon of Trent (1475)