If there was ever any doubt that the Catholic Church is not the true Church of Christ, one need only consider that whereas the Apostle Paul said let anyone preaching a different gospel be accursed (Galatians 1:8), the Catholic Church literally calls Paul's Gospel a sin. Catholicism maintains belief in what is commonly called the "sin of presumption", which
"...may be defined as the condition of a soul which, because of a badly regulated reliance on God‘s mercy and power, hopes for salvation without doing anything to deserve it, or for pardon of his sins without repenting of them." (1)
Biblically speaking, there is no such thing as a "badly regulated reliance" on God's mercy and power. In fact, throughout scripture, a major theme is that sinners must rely entirely on His mercy and power. By contrast, you will never find anything saying we must do anything to deserve salvation. Quite the opposite; the whole reason we need salvation is because we deserve wrath!
I challenge anyone, from any planet, to find even one Biblical reference to us having to do something to deserve salvation. Once you've found it, put the verse right back into context, then look at every reference about the wages of sin, comparing it very closely to how we obtain salvation. It is utterly repugnant to the Gospel that one should, or even could, do anything to deserve salvation. As Isaiah says, "But we are all like an unclean thing, And all our righteousnesses are like filthy rags; We all fade as a leaf, And our iniquities, like the wind, Have taken us away." (Isaiah 64:6).
The irony, then, is that while Catholic Encyclopedia suggests the "sin of presumption" "...may also be regarded as a product of pride", the sin of calling the Gospel a sin is a product of pride. Which sounds more pride filled: "I deserve salvation", or "Lord, have mercy on me, a sinner"? I'll give you a hint: The former exalts a sinful human being to a position of merited favor with God, whereas the latter, Jesus explicitly says sends a man to his house justified (Luke 18:9-14).
"Also He spoke this parable to some who trusted in themselves that they were righteous, and despised others: “Two men went up to the temple to pray, one a Pharisee and the other a tax collector The Pharisee stood and prayed thus with himself, ‘God, I thank You that I am not like other men—extortioners, unjust, adulterers, or even as this tax collector. I fast twice a week; I give tithes of all that I possess.’ And the tax collector, standing afar off, would not so much as raise his eyes to heaven, but beat his breast, saying, ‘God, be merciful to me a sinner!’ I tell you, this man went down to his house justified rather than the other; for everyone who exalts himself will be humbled, and he who humbles himself will be exalted.”"
Note, in this parable, the presumptuous one is not the one who relies entirely on the grace of God, but the one who doesn't. The one who believes he deserves God's attention is shown to be arrogant, whereas the man who knew he didn't deserve mercy nevertheless sought it. Is it any wonder, therefore, that Hebrews 4:16 tells us to come boldly before the throne of grace?
Grace, by the way, being something Catholics have no concept of. That's not to say they won't give lip service to it. Rather, like all false religions giving credence to scripture, they change the language. Biblically speaking, grace is defined not merely as unmerited favor, but demerited favor. It is God effectively saying "you deserve this punishment, but I love you, so I will instead take the punishment. I deserve this reward, but I took your punishment, therefore I will give you my reward."
In Catholicism, however, grace is handed out piecemeal. There's the initial grace that saves you, but in order to remain in a state of grace, you must be a good Catholic. How does this fit with, for example, Romans 11:6? "And if by grace, then it is no longer of works; otherwise grace is no longer grace. But if it is of works, it is no longer grace; otherwise work is no longer work." Answer: Not very well. Romans 11:6 is practically a dictionary definition, defining grace as being antithetical to works. It is no wonder, therefore, that Ephesians 2:8-10 reads "For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, not of works, lest anyone should boast. For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them." (Emphasis mine).
Ephesians 2:8-10 is so antithetical to the Catholic "gospel" that many Catholics, hearing it for the first time, and not knowing it's a direct quote from the Bible, will deny it. Only once they are familiar with the verse will they begin to reinterpret it to suit their "gospel". But the most natural interpretation is that we are saved by grace through faith, not of works, and that this is a gift, not something that is deserved. The good works are what we are saved to, not by.
With all of this in mind, it's no wonder John effectively concludes his first epistle by telling his readers "These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life, and that you may continue to believe in the name of the Son of God." (1 John 5:13).
You believe? You know you have eternal life.
You know you have eternal life.
You know you have eternal life.
Why? Because you deserve it? No, you're so corrupted with sin, even your righteousness is filthy rags to God. You know (no doubt) that you have (it's bought and paid for) eternal life because you believe in the name of the Son of God.
Well that's rather presumptuous of John. Uno problemo: It's John, writing under inspiration of God (2 Timothy 3:16-17). So unless you want to argue that John under inspiration of God, or worse, God Himself, can (and did) make a mistake, you must conclude that there is no sin in fully relying on God's mercy and power, knowing full well that you do no, and could not deserve salvation.
But there's more to the definition I appear to have ignored, isn't there? What about the part that says "...for pardon of his sins without repenting of them." But can any Catholic reading this honestly tell me they have repented of every individual sin they have ever committed? Of course not. Repentance isn't an individual action, it is a change of attitude. It is a war against the flesh. A statement that while we have the capacity to sin, and all too often obey that capacity, we have a capacity for Holiness, and should strive towards that. As my old pastor once put it, repentance is about being done with sin, even if sin is not done with me. In other words, repentance and faith are next door neighbors. No one, barring actual heretics with no faith, expects pardon of sins without repenting of them.
Under inspiration of God, the prophets and Apostles both encourage and exemplify the "sin of presumption". The Catholic Church, by contrast, encourages and exemplifies the self-righteousness of the Pharisaic order from which it seems to have taken its every cue, from its reliance on man made tradition to its tiny mannerisms such as calling priests "Father". Thus, the Catholic Church is revealed as an apostate Church, its "gospel" is exposed as a Satanic counterfeit, and its members are given yet another reason to flee, lest the doom of its teachers fall also on them.
References
1. Delany, J.(1911).Presumption. In The Catholic Encyclopedia. New York: Robert Appleton Company. (link)