I hear many Catholics saying that we must “cooperate” with grace - and while this language is proper to Catholic teaching, it must be qualified. Most Catholics are comfortable with the idea of “synergism.” But we know from the Council of Orange that even our willingness to cooperate with grace can only be brought about by grace; therefore, any “cooperation” in the process must be attributed to God working in us, and not to our selves. This is directly opposed to strict synergism.
From the Council of Orange:
Canon 4. If anyone maintains that God awaits our will to be cleansed from sin, but does not confess that even our will to be cleansed comes to us through the infusion and working of the Holy Spirit, he resists the Holy Spirit himself who says through Solomon, “The will is prepared by the Lord” (Prov. 8:35, LXX), and the salutary word of the Apostle, “For God is at work in you, both to will and to work for his good pleasure” (Phil. 2:13).
Canon 5. If anyone says that not only the increase of faith but also its beginning and the very desire for faith, by which we believe in Him who justifies the ungodly and comes to the regeneration of holy baptism — if anyone says that this belongs to us by nature and not by a gift of grace, that is, by the inspiration of the Holy Spirit amending our will and turning it from unbelief to faith and from godlessness to godliness, it is proof that he is opposed to the teaching of the Apostles, for blessed Paul says, “And I am sure that he who began a good work in you will bring it to completion at the day of Jesus Christ” (Phil. 1:6). And again, “For by grace you have been saved through faith; and this is not your own doing, it is the gift of God” (Eph. 2:8). For those who state that the faith by which we believe in God is natural make all who are separated from the Church of Christ by definition in some measure believers.
Canon 6. If anyone says that God has mercy upon us when, apart from his grace, we believe, will, desire, strive, labor, pray, watch, study, seek, ask, or knock, but does not confess that it is by the infusion and inspiration of the Holy Spirit within us that we have the faith, the will, or the strength to do all these things as we ought; or if anyone makes the assistance of grace depend on the humility or obedience of man and does not agree that it is a gift of grace itself that we are obedient and humble, he contradicts the Apostle who says, “What have you that you did not receive?” (1 Cor. 4:7), and, “But by the grace of God I am what I am” (1 Cor. 15:10).
Canon 7. If anyone affirms that we can form any right opinion or make any right choice which relates to the salvation of eternal life, as is expedient for us, or that we can be saved, that is, assent to the preaching of the gospel through our natural powers without the illumination and inspiration of the Holy Spirit, who makes all men gladly assent to and believe in the truth, he is led astray by a heretical spirit, and does not understand the voice of God who says in the Gospel, “For apart from me you can do nothing” (John 15:5), and the word of the Apostle, “Not that we are competent of ourselves to claim anything as coming from us; our competence is from God” (2 Cor. 3:5).