CYRIL OF ALEXANDRIA:
I now consider it my duty to mention why the door to life is narrow. Whoever would enter must first before everything else possess an upright and uncorrupted faith and then a spotless morality, in which there is no possibility of blame, according to the measure of human righteousness.… One who has attained to this in mind and spiritual strength will enter easily by the narrow door and run along the narrow way.
You may count certain others among those able to say to the judge of all, “We have eaten and drunk in your presence, and you have taught in our streets.” Who again are these? Many have believed in Christ and have celebrated the holy festivals in his honor. Frequenting the churches, they also hear the doctrines of the gospel, but they remember absolutely nothing of the truths of Scripture. With difficulty, they bring with them the practice of virtue, while their heart is quite bare of spiritual fruitfulness. These will also weep bitterly and grind their teeth, because the Lord will also deny them. He said, “Not everyone that says to me, ‘Lord, Lord,’ shall enter into the kingdom of heaven, but he that does the will of my Father who is in heaven.”