But that’s the amazing thing: in Christ, we can merit. God has consciously chosen to give us the possibility of making a difference in his Kingdom. We are not just along for the ride. What we do and how we choose to live our ordinary lives can actually increase the flow of grace in the world, spreading Christ’s Kingdom and storing up treasure for us in heaven. Jesus has not only saved us from damnation, but he has given us the possibility of becoming active, meritorious collaborators in the work of redemption. Not because we deserve it, but simply because he generously wanted to give us that possibility: he wanted our lives to have real meaning, our actions and decisions to have eternal repercussions. His love makes us friends and collaborators, not just his robots or spiritual trophies.
We cannot save or redeem ourselves; we need a Savior, a Redeemer: Christ. But on the other hand, once we have accepted Christ’s gift of grace, that very gift enables us to merit other graces for ourselves and for the Church. This is a marvelous, wonderful, and underemphasized part of the Good News!
—from the blog post “Offering It Up” – Redemptive Suffering Part I – The Mystery of Merit by Fr. John Bartunek at Roman Catholic Spiritual Direction
Sanctifying grace, union with Jesus, purity of intention, and fervor are four factors that help determine the degree of merit that our prayers, virtuous actions, and sufferings (sacrifices) can win for ourselves, the Church, and the world around us. So, to answer the original question, there is much more to uniting our sufferings to Christ than simply saying the words, though that is the necessary catalyst.
—from the blog post “Offering It Up” – Redemptive Suffering Part II – The Path to Greater Merit by Fr. John Bartunek at Roman Catholic Spiritual Direction