Flee also youthful lusts; but pursue righteousness, faith, love, peace with those who call on the Lord out of a pure heart. But avoid foolish and ignorant disputes, knowing that they generate strife. And a servant of the Lord must not quarrel but be gentle to all, able to teach, patient, in humility correcting those who are in opposition, if God perhaps will grant them repentance, so that they may know the truth, and that they may come to their senses and escape the snare of the devil, having been taken captive by him to do his will. (2 Timothy 2:22-26)
We are to call on the Lord with a pure heart according to the Apostle Paul. Purity of heart is not limited to sexual purity, but for the Apostle includes issues of faith, love, peace and anger. St John Cassian addresses the issue of purity of heart in terms of passions and vices especially that of anger. For St John it is not enough just to outwardly control our anger because we need to root it out of our hearts. God sees into our hearts and knows whether or not we are a peace lover and peacemaker or whether our heart is smoldering with anger even though we manage at times to contain it. Purity of heart means cutting out that anger from our hearts so that we no longer are embroiled in it.
Hence, if we desire to obtain in its entirety that divine prize of which it is said: ‘Blessed are the pure of heart, for they shall see God‘ (Matt 5:8), this must not only be cut off from our actions but must even be uprooted from the depths of our soul. For a wrathful anger that has been checked in speech and that has not manifested itself in deeds is of no value whatsoever if God, from whom the secrets of the heart are not concealed, sees that it exists in the recesses of our breast. For the words of the Gospel command that the roots of our vices be cut off rather than the fruits (Matt 3:10), which will certainly never grow any more once the shoot has been pulled up. And when they have been pulled up not from the surface of our deeds and actions but from the depths of our thoughts, our mind will then be able to abide in utter patience and holiness. (THE INSTITUTES, pp 202-203)
The garden of our heart must be tended with diligence to uproot the weeds (passions, vices) which try to establish themselves there. St Gregory of Nyssa encourages us to purify our hearts and souls:
… the man who purifies the eye of his soul will enjoy an immediate vision of God. . . . It is the same lesson taught by the Word [i. e. Christ] when He said, ‘The Kingdom of God is within you‘ (Luke 17:21).
This teaches us that the man who purifies his heart of every passionate impulse will see the image of the divine nature in his own beauty.
You must then wash away, by a life of virtue, the dirt which has clung to your heart like plaster, and then your divine beauty will once again shine forth (On the Beatitudes, Sermon 6). (Thomas Hopko, SPIRITUALITY, p 47)
Fraternized 