I was surprised to hear the other day that the hymn "Blessed assurance, Jesus is mine" is sung in some Catholic Churches. It is apparently popular among devotees of a more charismatic kind of worship. Although at a push, the hymn could be interpreted in a Catholic sense, it is certainly not intended to be so understood. "Blessed assurance" is a watchword among evangelical protestants, referring to the certainty of predestination and certainty of the gift of perseverance for those who are among the elect.
As Catholics we do believe in predestination, in the sense that God has prepared eternal bliss for those whom he foresees, in his infinite wisdom, will merit eternal life. Here on earth, we are not certain of our "election" or of final perseverance. Such supposed certainty is a sin of presumption. We pray with confidence to our heavenly Father, knowing his mercy but not taking it for granted.
Hence, the Council of Trent condemned the following errors:
If any one saith, that a man, who is born again and justified, is bound of faith to believe that he is assuredly in the number of the predestinate; let him be anathema. (Council of Trent. Canons on Justification. canon 15.)We do not have a "blessed assurance" but a blessed hope.
If any one saith, that he will for certain, of an absolute and infallible certainty, have that great gift of perseverance unto the end,-unless he have learned this by special revelation; let him be anathema. (canon 16.)