Remaining in the state of grace until the end of life. The Church teaches that it is impossible, without the special help of God, to persevere in the state of grace to the end. Thus the Second Council of Orange, in A.D. 529, teaches, in opposition to the Semi-Pelagians, that the justified also must constantly pray for the help of God so that they may attain to a good end (Denzinger, 380). And the Council of Trent in 1547 calls perseverance " a great gift" and says that those in the state of grace cannot persist in God's friendship without special divine aid (Denzinger 1572). Final perseverance cannot be strictly merited, as though a person had a claim on dying in grace because he or she had been faithful all through life. Nevertheless it can, with unfailing success, be achieved by proper prayer, offered regularly and earnestly, in the state of grace. The certainty of the prayer being heard is based on the promise of Jesus (John 16:23). since, however, the possibility of a fall always remains, one cannot know with infallible certainty whether one will, in fact, persevere unless one receives a special revelation to that effect (Council of Trent, Denzinger, 1566).