Dear SianTeresa,
3) The claim, made by a tiny faction of Orthodox practitioners of this breath/heartbeat method (hesychasts), and defended by Gregory Palamas (St Palamas in the Orthodox Church, but considered a heretic by Rome) that through the practice of the Jesus Prayer the disciple can attain the Beatific Vision while still in the body. This is another occasion of Messalian/Palagian heresy, saying that we can attain the gift of God’s loving presence by our works and our prayers. We can never attain the Beatific Vision by anything that we do, but only by God’s mercy. This error also opens hesychasm to a psychologistic error - by controlling heart-rate and breathing the hesychast acheives a bodily ecstacy, similar to that attained through the use of yogic exercise or the use of psychotropic drugs, and mistakes that neurological reaction for the experience of union with God. Ultimately, as Catholics, we do not pray in order to attain ecstatic experience, we pray because we wish to live lives pleasing to God.
1 and 2 are Catholic, 3 is heretical. As long as we understand that we are not praying the Jesus Prayer to ‘get’ anything from God, but only to put ourselves in a position where He can continue His sanctifying work in and through us, no problem. St John of the Cross is a great writer on the subject of mystical experience and how the Christian should not strive for visions and ecstatic experiences, but for the silent union of the soul with God in the darkness that lies beyond our sensory experience.
God bless.