Such is due to the fact that such is on the subjective side. We cannot change the matter itself that is grave…but what can enter in – that “makes it not a grave sin for me” is that lack of sufficient knowledge or consent. Such would not make that second and third aspects more important of course but rather --they are what is in our hands.
While I agree with most of what you offer, I disagree with the idea that, “We cannot change the matter itself that is grave…”
The reason is that, unlike in criminal law, we have no clearly defined cut-off point for what is a “misdemeanor” and a “felony” (venial or Mortal).
The most common response to the question “That is grave matter” is that grave matter a violation of the 10 commandments.
Yet it this always the case? Is willfully swiping a pen from a co-worker equally grave as robbing a bank?
We generally agree that it is not.
But in the case of criminal law there is a clear delineation, some dollar value, that separates the two. In the case of sin, there really is no clear delineation between what constitutes grave matter.
Sticking with the idea of theft, a poor man swiping a loaf of bread from a rich man is usually seen as venial sin. But a poor man swiping even less bread from another poor man is much more grave. Same “dollar amount” but much more grave sin.
So - To me - I don’t see any of the three conditions as being clearly delineated. What I do see is that any sin which will end in condemnation has to begin with the rejection of God, God’s Lordship, and God’s plan of salvation.
Perhaps a good biblical analogy is the phrase that we cannot serve two masters. That we will love one and despise the other or serve one and ignore the other. (Mt 6:24)
So - regardless of what we think we are doing or how we try to justify it, if we deliberately and willfully choose to sin (serve evil) then we cannot, at the same time, say that we are deliberately and willfully choosing to Love and serve God…At best we ignoring Him…at worst we are despising Him.
Peace
James