Why do we need a persistent prayer?

by St. John of Kronstat 

We need a persistent prayer so that we could warm up our hearts that became cold because of persistent worldly cares. It would have been strange to request such a heart to become penetrated with the warmth of faith and love of God  immediately upon starting one's prayer. For that to happen hard work and time are required. The Kingdom of Heaven is taken by force and those who put effort acquire it (Mt. 11:12). Not immediately the Kingdom of Heaven will enter the heart because men run away from it. The Lord Himself lets His will known to us by presenting the parable of the persistent widow who continually come to the judge and trouble him with her requests (Lk. 18: 4-5). Our Lord and God knows our needs even before we tell Him what we need; however, we do not know Him the way we should for we are loyal to our worldly cares  and not to our Heavenly Father. And that is why He, being compassionate and merciful, uses our needs as an excuse for us to turn to Him. Turn to Me, your Father, My lost children, with your whole heart. Even though before you were away from Me but now warm your hearts with faith and love towards Me.