First, let's talk about sin. When a man sins against God's law, he does not become a little less holy. Rather, he turns away from God. Sin results in not merely physical, but also spiritual death, ie, the soul's alienation from God. The soul is made for communion with its Creator, and when that communion is broken, the soul is effectively in hell. We might say this state is a living hell, whether or not it is perceived as such. As Luther said of Adam's spiritual condition after he sinned, "He was in the midst of death and hell." Sin does not result in being somewhat less holy; it results in utter unholiness, a rupture in one's relationship with God, which must be repaired.
What, then, is holiness? Holiness is the blessed life of communion with God. It is life as it was meant to be, life in its purest form. If I may borrow a thought from Saint John's Gospel, it is life in its abundance or fullness. As I say, the holiness of the soul is the state of being in communion with its Creator, to dwell in His presence. Now let me add, sort of parenthetically, that we may also speak of being in the holy presence of God, when, for example, we approach the altar and take our Eucharistic Lord into our bodies. And on that count, it is worth making a distinction. Entering into communion with God, say, for example, in the Holy Supper, does not in and of itself, make one holy. For if one is unprepared, then the presence of the holy God will have the opposite effect. It will harm the one who is unprepared, and confirm his unbelief. I am reminded of something David Scaer writes in one of his essays:
Unbelievers are kept away from the holy supper because their bodies are receiving what their souls despise, and they are tom apart in the very midst of their existence. Christ's body, intended to join human beings in the depths of their existence with God, becomes destructive of this unity and destines them to the most severe of all judgments. What unbelievers despise with their souls they eat with their mouths and it is joined to their bodies. An act of redemption becomes one of condemnation. They thrust themselves prematurely and unprepared before the judgment throne of Christ.As with Moses before the burning bush, so with us today. God draws close to us, and draws us close to Him, yet we dare not approach thoughtlessly or unprepared.
Now, what exactly is the proper preparation of which we speak? As intimated in the passage above, we are not speaking of some subjective or moralistic preparation. Rather, faith itself is what grasps the presence of God, and apprehends it. Looking at the more general question again, we are now able to answer the question of just what makes a man holy. The answer is simple. When we hear the Gospel, and receive it in faith, the soul is reconciled to God, and brought into communion with Him. As Luther writes of the spiritual condition of Adam and Eve after God preached the Gospel to them, promising the Savior:
This text it was that restored Adam and Eve to life and raised them again from death to the life which they had lost by their sin...This text is the absolution acquitting him and us all. For if this Seed is so strong that He crushes the head of the serpent, He also crushes all its power; so, then, the devil is conquered, and all damage which Adam suffered is repaired. Adam enters again the estate in which he was before.Which is to say that no matter what effects of sin we must suffer in this life, by faith in Christ we are even now in paradisal union with God.
To be sure, some Christians have a stronger faith than others, but it is not a certain level of strength that is required in one's faith for him to be worthy or prepared or able to receive God's gifts to his profit. We approach in faith, and bare our wounds, our shame, our weakness, which is to say, our weak faith, and what we receive in the Gospel, along with the forgiveness of our sins, is the edifying and strengthening of our faith. Faith itself is a gift, brought about by the Holy Ghost's work as He employs the powerful instrument of the Word. And all the gifts He gives us in the Church make us holy, for they bring us into the salvific communion with our loving Father in Christ.
There is such thing as increasing in holiness in this life. But it is not anything that I can accomplish by my own work. It is the work of God in me.
These are just some thoughts in response to what I think is a theologically sloppy mode of expression. And it is not to say that Roman Catholics would necessarily disagree with all I have written here. Nevertheless, these matters merit fleshing out. In fact, they merit more than I am giving them here.