Assurance

“In order that you should have steadfast assurance during prayer, of receiving every spiritual blessing from the Lord, believe that by uniting yourself unto the Lord during your prayer you become one spirit with Him (cf. I Cor. 6:17), and that God is most gracious, almighty and wise. He is all-perfect perfection, therefore, you, too, according to your perceptivity, according to your faith and love, will become a partaker of His Divine perfections. In the union of your soul with God, do not consider anything impossible or difficult of fulfillment, ‘for with God all things are possible’ (Mk. 10:27) – not only the things which you can think of, or are thinking of, but also those which you cannot think of, or which you think of as impossible, for God is an infinite Being, and all His perfections are infinite.”
~St. John of Kronstadt