The Biblical description of a "saint" is not some super-spiritual Christian but all those people whom God has called out of the world and set apart for himself through their faith in Jesus Christ. These people are expected to live holy lives, separated from the world, and reflecting the character of God. They have spiritual union with contemporary believers around the world, as well as with those who are already in heaven. An example of a fellow believer and martyr from the early centuries of the church would be Polycarp, bishop of Smyrna, who stood firm in his faith in Christ despite being killed for his belief. The distinguishing and necessary mark of a true believer is personal faith in the Lord Jesus Christ. This faith is marked by ongoing spiritual growth by conforming progressively more into the image of the Savior. Such people are commanded to "run with endurance" the race of life marked out for them, looking to Jesus, "the author and finisher of their faith," as well as to the example of the saints of previous ages, who were faithful to God in the midst of hardships and trials. As a living saint today, each believer has union with all believers who together are Christ's joy.