Balthasar begans by citing Aquinas to the effect that we cannot have "experiential certainty" as to whether we are in a state of grace, but that we can only reach natural certainty about it by voluntarily submitting to the Church's "norm of faith." Balthasar asserts that if the Angelic Doctor had left matters here that it would amount to what he calls fides informis, or a lifeless faith. I think some dispute could be made about this in light Jesus' initial proclamation at the beginning of His ministry, at least as His words are given in St. Mark's Gospel, which, when rendered literally, enjoin the hearer/reader "to be repenting and be believing" (metanoeite kai pisteuete; 1:15). To this Aquinas adds the donum infusum, or "infused gift." After all, faith is a theological virtue. My only point here is that, especially in light of Jesus' words, might not the donum infusum sometimes be facilitated, or increased (if one may write using a quantitative term in this context) by obedience? To be clear, he did indicate earlier that obedience is the fruit of faith and an act of hope, which is manifest by caritas.
Continuing with his exploration, Balthasar insisted that together the voluntary "psychological act of believing what the Church presents as dogma," along with "the donum infusum" only make-up the very beginning of "'faith' in the fullest sense." It is from here that he ventured forth to discuss an adult convert's faith. He wrote that, of course, such a person's confessio at the time of baptism is entirely sincere, at least from the human perspective. This confessio, Von Balthasar asserted, "is only the entry into a living relationship in the covenant with God." He noted that the real sincerity of the neophyte's confessio can only be demonstrated by how that person lives after making it; "whether to his own truth and will he seriously prefers the truth of God, which is expressed in God's will and law."
Then, after he held up Israel's covenant-relationship with God as an example, Balthasar wrote that the psychological act of gauging one's faith is always a dubious undertaking. "[W]ho can say to himself," he asked, "that he is living in accordance with the law of the Covenant, which in the New Testament is Christ himself?" He continued, "if faith is the freely given participation in the perfect covenant-fidelity of Jesus Christ, then this faith does not really belong to me in its origin and in its center, but to God in Christ." Hence, "I cannot grasp faith's supernatural reality to myself as if it were something belonging to me as a possession."
"Seen from this perspective," Balthasar concluded, "Christian experience can mean only the progressive growth of one's own existence into Christ's existence, on the basis of Christ's continuing action in taking shape in the believer: 'until Christ has taken shape in you' (Gal. 4:19)." Of course to be Christ-shaped is to be cruciform.
On this basis I can't help but note that it seems to me that this helps demonstrate the indispensable nature of the sacraments, which are the primary means, or tools, Christ uses to finish the "good work" He began in the believer (Phil 1:6). Through the sacraments we are drawn deeper into the reality of our own everyday experience, which experience, to borrow the title from Communion and Liberation's 2009 La Thuile Assembly, is "the instrument for [our] human journey."
Leitourgia is not primarily our work, but Christ's work, one from which and into which our "work" flows, our work being askēsis, which gets us back to being repenting and being believing, or obeying freely on the basis of faith, acting with hope, which is manifested in love. Such obedience is always a choice, but God's love, especially as manifested in the sacrament of mercy, is always greater than our failures, our bad choices. This why the fruit of the fifth Sorrowful Mystery of the Most Holy Rosary of the Blessed Virgin Mary is persistence, or why Christ, in St. John's Gospel, repetitively enjoins His disciples, not to merely "abide" with Him, but to "adhere," that is, "stick to Him."
Jesus, I trust in You.