You ask for some way of completely eradicating irritability. The inclination to irritability is given us to use against sin, and we were never meant to use it against our fellow men. When we do, we act contrary to our true nature.
Faith is truly a gift, gained for us through Christ's advent. But this does not abolish our freedom or responsibility. God desires of us not only faith but action too.
The Holy Fathers recommend 'moderate' fasting; one ought not to allow the body to be weakened too much, for then the soul, too, is harmed. Nor ought one to undertake fasting too suddenly; everything demands practice, and each one should look to his own nature and occupation. To choose among different kinds of food is to be condemned; all food is God-given, but it is advisable to avoid such kinds as add to the body's weight and appetite; strong spices, meat, spirituous drinks and such foods as are solely for the palate's enjoyment. For the rest, one may eat what is cheap and most easily available, they say. But by 'moderate' they mean one meal a day, and that one light enough not to fill the stomach to satiety.
Sear your loins by abstaining from food, and prove your heart by controlling your speech, and you will succeed in bringing the desiring and incensive powers of your soul into the service of what is noble and good.
The enemy constantly endeavors to awaken in the abyss of the human heart a great turmoil about trifles. This is one of his tricks to blind our soul to the sun of truth, Christ our Lord, hidden in the heart's core of every one of our neighbors.
It is well known that obedience is the chief among the initiatory virtues, for first it displaces presumption and then it engenders humility within us. Thus it becomes, for those who willingly embrace it, a door leading to the love of God. It was because he rejected humility that Adam fell into the lowest depths of Hades. It was because He loved humility that the Lord, in accordance with the divine purpose, was obedient to his His Father even to the cross and death, although He was in no way inferior to the Father; and so through His obedience He has freed mankind from the crime of disobedience and leads back to the blessedness of eternal life all who live in obedience. Thus humility should be the first concern of those who are fighting the presumption of the devil, for as we advance it will be a sure guide to all the paths of virtue.
All men are made in God's image; but to be in His likeness is granted only to those who through great love have brought their own freedom in subjection to God... Free will is the power of a deiform soul to direct itself by deliberate choice towards whatever it decides.
But, say the saints, now that you recognize the darkness in your own heart and the weakness of your flesh, you lose all desire to pass judgment on your neighbor. Out of your own darkness you see the heavenly light that shines in all created things reflected the clearer: you cannot detect the sins of others while your own are so great. For it is in your eager striving for perfection that you first perceive your own imperfection. And only when you have seen your imperfection, can you be perfected. Thus perfection proceeds out of weakness.
Wherever we are and whatever our circumstances, the enemy always tries to prevent us from actively responding to the call. Pray for help. For help that you may never fail to respond. And beware lest, having received help and having done the right deed because of it, you should grow proud and acquire the habit of condemning others, in the secret chambers of your heart. Beware! For this would make all the fruits of your good works wither.
Keep your mind from malicious thoughts of your neighbors, knowing that such thoughts are hurled by diabolical power, to keep your mind from your own sins and from seeking.
Pray simply. Do not expect to find in your heart any remarkable gift of prayer. Consider yourself unworthy of it. Then you will find peace. Use the empty cold dryness of your prayer as food for your humility. Repeat constantly: I am not worthy; Lord, I am not worthy! But say it calmly; without agitation.
Take remarks without grumbling: be thankful when you are scorned, disregarded, ignored. But do not create humbling situations; they are provided in the course of the day as richly as you need. We notice the person who is for ever bowing and fussily servile, and perhaps say, How humble he is! But the truly humble person escapes notice: the world does not know him (I John 3:I); for the world he is mostly a 'zero.'
When you go to your spiritual father for confession, do not bring yourself as an accuser of other people, saying, 'he said this,' and 'so-and-so said that'. . . but speak about your own doings, so that you may obtain forgiveness.
Those pursuing the spiritual way should train themselves to hate all uncontrolled desires until this hatred becomes habitual. With regard to self-control in eating, we must never feel loathing for any kind of food, for to do so is abominable and utterly demonic. It is emphatically not because any kind of food is bad in itself that we refrain from it. But by not eating too much or too richly we can to some extent keep in check the excitable parts of our body. In addition we can give to the poor what remains over, for this is the mark of sincere love.