The idea of merit has a biblical basis. The Church didn't invent the idea of merit to fit an already predetermined system of theology. Rather, centuries of saints and theologians have read, again and again from the same texts of scripture, about the God who rewards.
That's really what we mean by "merit": God has promised to reward those who love him. Protestants, on the other hand, for one reason or another, get shaken up by the idea of merit. I recently listened to Jimmy Akin, from Catholic Answers, clarify on one protestant podcast, that merit is not the same thing as "earn". To earn something is to have a strict right to it, as if the one who is paying you the earnings is stricly obliged to give it.
That's not the case with merit. Merit is not earned, but is given on the basis of the promises of God. Big difference; and it's this difference that makes the Catholic idea of merit biblical. Any expectation whatsoever to be rewarded a prize for loving God and loving neighbor in the concrete acts of daily life, is problematic for many a protestant ear. But that might be because we—speaking of us Catholics here—have not done a sufficient job at explaining the basis for our hope in receiving a reward from God. That basis is, as said above, based on and grounded in the promises of God.
But this is not an apologetic article. Rather, what I would like to do is help bring this idea of merit and reward forward for those of us building apostolates here in Los Angeles. It's helpful to remind ourselves of what it is we are doing and the way in which we should categorize such apostolic works in their theological context. To do this, then, I would like to quote at length the work of the very reverend, Adolphe Tanquerey, from his work The Spiritual Life: A Treatise on Ascetical and Mystical Theology.
First, Tanquerey writes about the nature of merit itself. "Merit in general," he says, "is a right to a reward." Good enough; but he goes on to make one all-too important clarification:
"Hence, supernatural merit of which we speak here is a right to a supernatural reward, a right to a share in God's life, a right to grace and glory. Since, however, God is in no way obliged to make us share in His life, there must exist a promise on His part that confers upon us an actual title to such supernatural reward. Merit, then, may be defined: a right to a supernatural reward arising both from a supernatural work done freely for God's sake, and from a divine promise to give such a reward" .
Never have I read a more perfect definition of the biblical, and thus Catholic, concept of merit. Call this de congruo merit if you'd like (distinct from strict merit or de condigno merit), but the point is nevertheless this: the basis of our expectation to receive a reward is in the promises of God, which, as it turns out, gives us strong hope that God will rewards us for our apostolic work.
I have often wondered that, had God not wanted us to be motivated by seeking a reward, why would He have tried to motivate us to seek the reward? Over the years, I have come to the conclusion that the reward is not revealing something about us per se, but clearly God wants to be known as a God who gives rewards, a God who, according to what He has promised, has in fact promised to reward those who love Him and others, and express that love in action.
All this brings us forward to what Tanquerey calls the "conditions for increasing merit," that is, conditions on the part of (a) this or that particular person performing apostolic work in Los Angeles, as well as the conditions on the part of (b) the particular act itself.
Concerning the conditions for increasing merit on the part of the one who merits, Tanquerey puts forth four principal conditions:
The degree of habitual grace or charity: "The value of an act even in human affairs depends largely upon the dignity of the person that performs it, and upon the degree of esteem in which he is held by the rewarder. Now, what constitutes the dignity of the Christian and what makes him dear to the heart of God is the degree of grace, that is, of divine life to which he has been raised" .
Our degree of union with our Lord: "The source of our merit is Jesus Christ, the Author of our sanctification, the chief meritorious cause of all supernatural good, the Head of the mystical body whose members are we. The closer we are to the source, the more we receive of its fulness; the closer we approach to the Author of all holiness, the more grace we receive; the closer we are to the Head, the more life and activity it imparts to us" .
Purity of intention: "For our actions to be meritorious it is enough, according to many theologians, that they be inspired by any supernatural motive: faith, hope and love... The intention is the principal element in our actions; it is the eye that sheds its light upon them and directs them towards their end; it is the soul that animates them and gives them their worth in God's sight: 'If they eye by single, thy whole body shall be lightsome'" .
Fervor or intensity of our actions. "Even in the accomplishment of good works, it is possible for us to be careless and remiss; or, on the other hand, we may act with vigor, with all the energy at our command, making use of all the actual graces placed at our disposal. Evidently, the result in either case will be different. If we act halfheartedly we acquire but little merit and at times become guilty of venial sins, which do not, however, entirely destroy our merit. If, on the contrary, we pray and labor and sacrifice ourselves whole-heartedly, each of our actions merits a goodly share sanctifying grace" .
These are all good reminders, and Tanquerey does a good job supplying us with a thorough treatment of why our apostolic endeavors in Los Angeles are rewarded by our Lord and serve to please Him.
Tanquerey's final analysis, concerning the conditions on the part of the act itself that serve to increase merit, struck me as forgotten and overlooked (speaking for myself). As he says,
"Subjective dispositions are not the only conditions that increase merit; there are also objective circumstances that contribute to render our actions more perfect" 
That's right, and as he points out, there are four:
The excellence of the object. "There is a hierarchy among the virtues; the theological excel the moral. Hence, the acts of faith, hope and charity have greater worth than those of prudence, justice, temperance, et. But, as we have said, the latter can, through the intention of the subject, become also acts of charity and thus share in the special worth that attaches to this virtue. In like manner acts of religion which of themselves have God's glory directly in view, are more perfect than those that look directly to our sanctification" .
The quantity can also increase the excellence of the object. Giving $1,000 is more meritorious than giving $100, although, as Tanquerey points out, this can be relative to each person, since the widow deprived herself of more even though she objectively gave less. The point is taken: to deprive oneself of $1000 is more than to deprive oneself of $100.
So too, the duration of an act can render it more meritorious. To suffer in love for a long time is much more than to suffer for a short period of time.
And finally, the difficulty, "not precisely inasmuch as it is a difficulty, but inasmuch as it demands greater love and a more strenuous and sustained effort." He goes on, "For example, to resist a violent temptation is more meritorious then to resist a light one; to practice meekness with a choleric temperament and in spite of frequent provocations from others is more difficult and more meritorious than to do so with a nature that is gentle and mild or when others are kind and considerate. We must not conclude, however, that the ease acquired by the repetition of virtuous acts necessarily diminishes our merit. Such facility, when used to sustain and to strengthen the supernatural effort, contributes to the intensity or fervor of the act, and in this way it rather increases our merit, as we have already explained above. Just as an efficient worker in the measure that he becomes proficient in his work avoids all waste of time, material and energy, and thus realizes larger gains with less labor, so the Christian who has learned to make better, and thus with less trouble to himself gains greater merit. Because the Saints through the practice of virtue make acts of humility, obedience, religion, with greater facility, they are not therefore entitled to less merit; just the contrary, since they make acts of love of God with greater ease and frequency. Moreover, they continue their efforts to make sacrifices whenever necessary. In short, difficulty increases merit, not inasmuch it is an obstacle to be overcome but inasmuch as it calls for more energy and more love" .
What does this matter, and what does it have to do with our apostolic work in Los Angels? It matters because, as it would turn out, it matters to God Himself. The original promise made to those who love God and their neighbor is not a trivial promise. It's something to think about deeply, something to stir over in our minds and hearts, namely, that God wants to reward us. Again, if we can remove the reactionary-protestant-impulse that might creep into our minds every now and then that tells us God can't reward, we can begin to see that being motivated by God's goodness is a testament to God's good character, that He keeps His promises, and that the reward is part of His glory. The Council of Trent said virtually the same thing, quoting St. Augustine, that when God crowns our merits, he crowns his own gifts! This was actually about God all along. Jesus places considerable emphasis on rewarding His followers, not because the four Gospel's happen to feel "Catholic" and the Pauline epistles happen to feel "protestant", but because the goodness and love of God is the glory that is His divine nature.
Granted our whole disposition before God is one of grace. No one can stand before God and demand anything. That's not new to the New Testament. Abraham and David knew that, as did Jeremiah and the prophets. The balance of the two points—God's goodness that rewards us and God's grace that keeps us—should be the trail the Spirit blazes in our hearts as we continue our apostolic mission here in Los Angeles.
But we do well not to dissolve into thinking God will not reward His children; He is a Father after all (and the perfect One at that). Not only do we need to remind ourselves of the need for fellowship with each other, but we also need to know that God is a rewarding God, who redefines our missiological and soteriology context in familial and covenantal terms. This new people God has formed, what we call the Church, is, of course, God's own family. We do well to live as if He is our loving Father.
Jesus and Mary, be with us on the way
May God reward you for your efforts, my fellow Catholic angelenos!
 Tanquerey, Adolphe. The Spiritual Life: A Treatise on Ascetical and Mystical Theology. N.p.: Tan Books, 2013, p. 120.
 Ibid, 123.
 Ibid, 124.
 Ibid, 125-6.
 Ibid, 127.
 Ibid, 128.
 Ibid, 128-29.