The temptation comes in accordance with one’s stature. And you must endure in order to emerge victorious. Christ, Who sets the contest, allows temptations for this reason: so that we may gain victories against the enemy, be purged from passions, and be perfected.
It is more serious to lose hope than to sin. The traitor Judas was a defeatist, inexperienced in spiritual warfare; as a result he was reduced to despair by the enemy's onslaught, and he went and hanged himself. Peter, on the other hand, was a firm rock: although brought down by a terrible fall, yet because of his experience in spiritual warfare he was not broken by despair, but leaping up he shed bitter tears from a contrite and humiliated heart. And as soon as our enemy saw them, he recoiled as if his eyes had been burnt by searing flames, and he took flight...
You write that after Communion you felt well. Glory be to God, Who comforts our unworthiness. And as regards the fact that this soon passed, here also is seen His fatherly providence for us. For continual consolation enfeebles the soul and makes it slothful, or leads to even greater harm. That is why the Lord takes it away quickly and again makes us feel our weakness, our helplessness, and our sinfulness. We must humble ourselves more, reproach ourselves, offer repentance for our sins, and not desire consolations, but patiently endure what God allows. Dryness and cooling of fervor are also permitted on account of vainglory.
He who is obedient, is an imitator of Christ, and he who is proud and talks back is an imitator of the devil. So let us be careful, whom we are imitating, Christ or the devil…The so-called Christians must be true, in word and deed and not false, only in name.
Whatever gentleness you use in speaking with others, that very same gentleness will Christ use with you. With whatever measure you measure out to others, with that very same measure will He apportion out to you. Just as you forgive the failings of others, He forgives yours. With whatever love and gentleness you seek Him, likewise will He appear to you.
Even a pious person is not immune to spiritual sickness if he does not have a wise guide -- either a living person or a spiritual writer. This sickness is called prelest, or spiritual delusion, imagining oneself to be near to God and to the realm of the divine and supernatural. Even zealous ascetics in monasteries are sometimes subject to this delusion, but of course, laymen who are zealous in external struggles (podvigi) undergo it much more frequently. Surpassing their acquaintances in struggles of prayer and fasting, they imagine that they are seers of divine visions, or at least of dreams inspired by grace. In every event of their lives, they see special intentional directions from God or their guardian angel. And then they start imagining that they are God's elect, and often try to foretell the future. The Holy Fathers armed themselves against nothing so fiercely as against this sickness -- prelest.
God often permits virtuous men to be tried by something: He permits temptations to rise up against them on all sides... Whether these trials come from men, demons or flesh, let it be a cause for thanksgiving. For God cannot show his favor to a man who desires to dwell with Him, except by sending him trials for the sake of truth; just as no man can become worthy of this greatness... without the grace of Christ... St. Paul plainly calls it a gift... 'For unto you it is given in behalf of Christ, not only to believe in Him, but also to suffer for His sake' (Phil. 1:29).
A small affliction borne for God's sake is better [before God] than a great work performed without tribulation, because affliction willingly borne brings to light the proof of love.