Every man is given the graces necessary to save his soul – no one is born who cannot be saved. But some people are predestined to receive greater graces than others. Why? The inscrutable mind of God.
Who receives greater merit? Merit is dependent on how much we respond positively to the graces offered, it is not inversely related to how much grace we are given (as though we were rewarded for the increased effort necessary on our own part) but directly related to how much grace we are given.
If you could quantify grace (which, of course, you can’t) then say Alice was given 100 units of grace at birth. She accepts 20 of these units, God gives her 10 more of which she accepts 7. So thus she has ends up with 27 units of grace. Bob was given 50 units of grace at birth, he accepts 35 of them, God gives him 40 more units of grace, of which he accepts 23. Thus he ends up with 58 units of grace. So Alice started off with more grace but ended up with less. Therefore, Bob’s reward in heaven is greater than Alice’s because he was more receptive to God’s grace.
If merit was inversely related to grace, then Our Lord and Our Lady would have merited little or nothing when in fact Our Lord merited infinitely and Our Lady merited more than all other creatures combined (although not infinitely, being a finite being but a superabundance).
St. Louis de Montfort says:
Mary merited more than all the martyrs combined because of the purity of her intentions. St. Lawrence or any of the other martyrs were great saints and gave their lives in horrific ways to the greater glory of God but Mary gave more glory to God in a single stitch than all the martyrs combined, why? Because of the superabundance of grace in her soul.
This is also why great saints barely say a Hail Mary and God is ready and willing to give them whatever it is they desire whereas the rest of us pray and pray for years and barely get anywhere. This is the result of merit. The great saint is so perfectly conformed to the will of God that what they will and what God wills are almost perfectly aligned (and for the Blessed Virgin and Our Lord’s human will, they
were perfectly aligned) whereas for most of us, we suffer selfishness and ignorance about what is right and most useful for the salvation of our soul and of the world.
This alignment of our will with God’s will is what gains merit. This can only be done through grace since grace is the life of God in the soul. Therefore, the amount of merit a person has is directly proportionate to the amount of grace that a person has in their soul.
Some people are born especially predestinate, such as Our Lady but also the great Prophets of the OT and the great saints of the NT. God always raises up saints to himself by pouring out his grace abundantly upon a person so although it is certainly not impossible for them to sin and they do indeed sin (Our Lady, of course, excepted), they quickly rise back up and continue their climb towards heaven. St. Therese talked about her “elevator” to heaven of her “Little Way” compared to those who climbed the arduous stairs to perfection. God allows everyone some crack of light which they can pursue to find heaven but for some people, it seems He only allows a little crack of
darkness for them run away from Him into – that He makes it very difficult (although not impossible) for them to fall into hell. Most of us are somewhere in between. This is the part of the mystery of Predestination.
This is one of the best books on the subject of Predestination:
ecx.images-amazon.com/images/I/51D56PK87HL.BO2,204,203,200_PIsitb-sticker-arrow-click,TopRight,35,-76_AA300_SH20_OU01.jpg