Canon Michael Wiener of the Institute of Christ the King Sovereign Priest kindly sent me the text from his sermon today:

Seek ye therefore first the Kingdom of God,
and His justice
Holy Mother Church teaches us by good example.
Good examples are available by the thousands: The lives of the saints give an example of how one can allow oneself to be modeled successfully according to the image of God, the perfect image of the Master. 
Less frequently the Church presents to us bad examples, examples of sin and of refusal to respect and love the will of God: Solomon and his fall, the sinful rich man who ignores the beggar Lazarus wishing to be fed with the crumbs that fell from the rich man’s table – and Judas, the traitor among the apostles, the “son of perdition”. Judas is presented as the chief example of unfaithfulness and rejection of the love of Christ. Judas is one of the few if not the only one of whom we know is in hell.
Judas’ sin of delivering Our Lord is related to the sin of avarice, some say that avarice is the source and beginning of the final sin of delivering Jesus into the hands of his enemies.
“There are two kinds of avarice”, says St. Francis de Sales: “One is temporal, and it is that by which we are avid to acquire wealth, honors and the goods of this life.” The other kind of avarice “clings to what it has and is unwilling to part with it for anything.” Saint Francis explains: “This is highly dangerous and steals in everywhere, even into religion and into spiritual things. We may indeed restrain ourselves from the first kind of avarice, for there are many persons who are not ambitious for amassing much property, fields and houses. But they are few who easily part with what they possess. We find married men with children and a family, for whom they should acquire some things so as to provide for their needs, but who are nevertheless not at all concerned to do this. They squander and dissipate all their substance, and remain poor, weak and miserable all their lives. Yet, they are so avaricious for their freedom, which is their treasure, their wealth, and the noblest thing they have that they cling to it … and will surrender it for nothing else in the world.”
Judas, teaches the holy Doctor, was avaricious with these two kinds of avarice which we have just treated. He was avid to amass riches, to obtain money and more money, and he also concealed and clung to it. “The avaricious man makes a god of his gold and silver”, says Holy Scripture in various places.
What makes the case of Judas’ fall so spectacular is the fact that despite his closeness to the Lord he allowed his interests in money and riches to take the place of faith in and love for the Lord.
In sin the human person confuses means and ends. The things on earth ought to be used as means to our final end, which is Heaven, not as ends in themselves; while the things of God indeed are our final end, and should not be looked upon simply as helps to make this world a more gracious place to live.
“There would have been no wrongdoing at all in carrying the purse and managing the money if he had done as he should, but this disloyal and miserable man did not conduct himself as a faithful procurator, but rather as a thief and a miser. … So that from being an Apostle that he was, he became a devil and sold his Master for money.”
Of course, what aggravates the sin of avarice in the case of Judas is the fact that he was a priest, called and empowered to live out the priestly character in him, to live according to the character of Christ. Avarice and all kinds of purely worldly interests seem to be especially incompatible with the priestly vocation. However, it is especially in priests that these things find roots and attraction.
“Worldliness! Love of stocks and bonds! Luxury! Alcohol! Mention any sin that comes to mind. These are the tails on the falling kites of the priesthood”, says Bishop Fulton Sheen. “But there was already a tear in the garment of holiness before these other forms of nakedness and shame appeared. Our Lord knows where all such overt and scandalous sins started. Maybe they started in a ‘fifteen-minute Mass’, a ‘one-minute thanksgiving’ after Mass … But somewhere, somehow, the man who is a priest because of the Eucharist failed to be a Eucharistic priest.”
Bishop Sheen makes the point very clearly that the sin of avarice which is on the surface of the final sin of Judas is mentioned in the context of Eucharistic piety: “Jesus therefore, six days before the Pasch, came to Bethany, where Lazarus had been dead, whom Jesus raised to life.” And when Mary took a pound of precious ointment and anointed the feet of Jesus and wiped his feet with her hair, and the house was filled with the odor of the ointment, Judas said: “Why was not this ointment sold for three hundred pence and given to the poor?”
“It was Judas’ lack of faith that hardened his heart and confirmed him in his greed”, says Fulton Sheen. The lack of faith became especially obvious and destructive, we can say, in the moments when Jesus prepares his disciples for His continued presence in the Eucharist: In Bethany and at the last supper. 
In such an Eucharistic moment our Lord makes even the last attempt to save Judas from his own hardened heart.
“He that dips his hand with me in the dish, he shall betray me. The Son of man indeed goes, as it is written of him. But woe to that man by whom the Son of man shall be betrayed.”
And the Lord continues to offer rescue and help in our weaknesses especially effectively in our Eucharistic moments. Only an ever renewed Eucharistic piety, a faithful application of all liturgical wisdom and discipline can help us to keep the eyes directed toward heaven. Only if we allow our heart to be formed and reformed by the graces of God coming to us in the channels of the Sacred Liturgy, we can defend ourselves against our own sinfulness. Only if we learn again and again to see God as our final end, and not as our crutch to make this world a more gracious place to live, we will be able to overcome our sinful attachments to those things which were given to us to find God and to love Him in all eternity.
Seek ye therefore first the Kingdom of God,
and His justice