There is only one thing you must fear: sin. When the court of the Greek emperor held a meeting to discuss the question of how to take revenge on Saint John Chrysostom for his forthright denunciation of the empress, the following plans were suggested:
a) Cast him into prison. “But there he will have the opportunity to pray and suffer for the Lord as he has always desired.”
b) Banishment. “But, for him, everywhere is the Lord’s country.”
c) The death penalty. “But, thus he will be a martyr and he will satisfy his aspirations to go to the Lord. None of these plans will cause him to suffer; on the contrary, he will joyfully accept them.”
d) “There is only one thing of which he hates above all else – sin; but it would be impossible to force him to commit sin!”
Therefore, if your only fear is sin, no one will be stronger than you. (Cardinal Van Thuan, Five Loaves and Two Fish)
Reflection
This fear of sin moves us into the truth of who we are and also moves us into a deeper interaction with others. Thomas Merton, in The Inner Experience: Notes on Contemplation, writes:
Thus the man with the “sacred” view is one who does not need to hate himself, and is never afraid or ashamed to remain with his own loneliness, for in it he is at peace, and through it he can come to the presence of God. More still, he is able to go out from his own loneliness to find God in other men. That is to say, in his dealings with others he has no need to identify them with their sins and condemn them for their actions, for he is able, in them also, to see below the surface and to guess at the presence of the inner and innocent self that is the image of God. Such a man is able to help other men to find God in themselves, educating them in confidence by the respect he is able to feel for them. Thus he is capable of allaying some of their fears and helping them to put up with themselves, until they become interiorly quiet and ‘learn’ to see God in the depths of their own poverty.
This is why the one who fears sin is such a threat to the “world”. As the fear of sin liberates us to encounter our true selves; we unconsciously give other people both permission and witness to do the same.
Cherish one desire: “Thy kingdom come; Thy will be done on earth as it is in heaven” (Mt 6:10), so that throughout the earth all nations will know God as he is known in heaven; so that on this earth everyone will begin to love one another as in heaven; so that also on this earth there will be the beatitude that there is in heaven. Make the effort to spread this desire. Begin now to bring the happiness of heaven to everyone in this world. (Cardinal Van Thuan, Five Loaves and Two Fish) 
The Alternate Path 