The Catholic Church does not teach grace alone when it comes to salvation.

Catholics who claim that we are saved by grace alone are simply using the same illogical formulary that Protestants use when they say that:

We are saved by faith alone but the faith by which we are saved is not alone.

That is self contradicting whether you use the word faith or grace.  And two contradicting statements can not be true at the same time.

Now they want to claim that we cooperate with grace alone.  And they call that the Catholic doctrine of grace alone.  It is false.

Yes, it is true that ALL IS GRACE.   Because God caused everything by His grace.  But the Catholic Church has always made a distinction between Creation (Monergism) and Salvation (Synergism).  It is most clearly explained by St. Augustine.

1847 "God created us without us: but he did not will to save us without us." To receive his mercy, we must admit our faults. "If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just, and will forgive our sins and cleanse us from all unrighteousness."

The Catholic Church does not teach monergism when it comes to salvation.  The Catholic Church does not teach grace alone when it comes to salvation.

The Catholic Church does NOT teach grace alone

Apparently, some Catholics believe that the Catholic Church teaches grace alone.  It doesn't.

Grace alone and irresistible grace are the same doctrine and they deny the Catholic Teaching of freedom of will which man can exercise in cooperation with God to achieve his salvation.  Protestants coined the term grace alone to directly contradict the Teaching of the Catholic Church. And the Catholic Church condemned that teaching in the Council of Trent.

Canon 4.If anyone says that man's free will moved and aroused by God, by assenting to God's call and action, in no way cooperates toward disposing and preparing itself to obtain the grace of justification, that it cannot refuse its assent if it wishes, but that, as something inanimate, it does nothing whatever and is merely passive, let him be anathema. 

In debates with Protestants concerning grace, they frequently charge Catholics as being pelagian or semipelagian because we don't embrace grace alone.  But the Catholic Church has condemned all three.  I didn't realize that some Catholics have fallen into the trap of accepting this Protestant formulation.  To me, it indicates that those Catholics who are fooled into this trap simply don't understand that which the Church has condemned nor that which the Church teaches. 

The Catholic Church condemns all three as false doctrines. The Catholic Doctrine of synergism is not equivalent to pelagianism or semipelagianism.

Here is the meaning of semi Pelagianism from the Catholic Encyclopedia.  Note that it distinguishes between Pelagianism, semipelagianism and the true Catholic Doctrine:

1. In distinguishing between the beginning of faith (initium fidei) and the increase of faith (augmentum fidei), one may refer the former to the power of the free will, while the faith itself and its increase is absolutely dependent upon God;

So, semipelagianists taught that conversion was initiated by the free will of the man. Whereas, the Catholic Church teaches that the prevenient grace also known as the call of God to conversion is completely God’s initiative.

2. the gratuity of grace is to be maintained against Pelagius in so far as every strictly natural merit is excluded; this, however, does not prevent nature and its works from having a certain claim to grace;

Unlike strict Pelagianism, semipelagianists claim that grace is free. Still, they claim that doing good works forces God to provide grace.  The Catholic Church teaches similarly and this is probably the biggest source of confusion.

The best way to explain it to you is to show the example of the Old Testament Jews.  Notice that in Scripture, the faithful Jews did not enter heaven until Jesus Christ died upon the Cross.  

Hebrews 11:39-40
39 And these all, having obtained a good report through faith, received not the promise:40 God having provided some better thing for us, that they without us should not be made perfect.

So, it didn't matter how much they did.  Even though God approved of them, He did not admit them to His presence until Christ died upon the Cross.  And it is the same for us.  Unless Christ died upon the Cross, we would not be accepted into heaven.  No matter how much we do.  Do you see how our works do not leverage our salvation?  If Christ had not died for us, we could not be saved.  
That doesn't mean our works are not important.  No one can be saved who does not obey the Son of God:

Hebrews 5:9

9 And being made perfect, he became the author of eternal salvation unto all them that obey him;

3. as regards final perseverance in particular, it must not be regarded as a special gift of grace, since the justified man may of his own strength persevere to the end;

As in #1, they claimed that a man may persevere of his own will and strength. This they held in common with Pelagianists. And it is against Catholic Teaching since we believe that without God’s grace a man can not persevere to the end.

4. the granting or withholding of baptismal grace in the case of children depends on the Divine prescience of their future conditioned merits or misdeeds.

I don’t understand that one. But I don’t need it in order to distinguish between it and Catholic Doctrine on grace.

Rejecting grace alone does not make the Catholic Church pelagianist or semipelagianist.  Don't buy into that Protestant lie.  Grace alone contradicts Catholic Teaching on free will and cooperation with God's grace.  Grace alone is a Protestant heresy.

Why would we not admit it 100 % of the time?

ZW:

And when devout Catholics have a spat of honesty or they have been drinking, they admit they believe they can merit eternal life and that proudly.

It is the truth which Scripture teaches. Why would we not admit it 100 % of the time?

1 Timothy 4:16

King James Version (KJV)
¹⁶ Take heed unto thyself, and unto the doctrine; continue in them: for in doing this thou shalt both save thyself, and them that hear thee.

Here's the difference between Catholics and Protestants. The Church teaches us to participate in our own salvation, in obedience to Christ:
Hebrews 5:9

King James Version (KJV)
⁹ And being made perfect, he became the author of eternal salvation unto all them that obey him;

Whereas, Protestants teach people to reject that teaching. And to save themselves according to their faith "alone". Which contradicts Scripture:
James 2:24

King James Version (KJV)
²⁴ Ye see then how that by works a man is justified, and not by faith only.

They claim to judge themselves saved. Which contradicts Scripture:
1 Corinthians 4:3

King James Version (KJV)
³ But with me it is a very small thing that I should be judged of you, or of man's judgment: yea, I judge not mine own self.

They claim to know better than the Church. And that contradicts Scripture:
Ephesians 3:10

King James Version (KJV)
¹⁰ To the intent that now unto the principalities and powers in heavenly places might be known by the church the manifold wisdom of God,

They claim they don't have to obey anyone in the Church. And that contradicts Scripture:
Hebrews 13:17

King James Version (KJV)
¹⁷ Obey them that have the rule over you, and submit yourselves: for they watch for your souls, as they that must give account, that they may do it with joy, and not with grief: for that is unprofitable for you.

They claim that no one can teach them anything about their faith. And that contradicts Scripture:
Hebrews 13:7

King James Version (KJV)
⁷ Remember them which have the rule over you, who have spoken unto you the word of God: whose faith follow, considering the end of their conversation.

In this, they have much in common with the world, because those of the world that believe in an afterlife believe they too save themselves with their works. Ironically, like most Catholics, the worldly also believe they have been good enough to merit eternal life if they died today.

On the contrary. We leave it up to God to judge the merit of our works. It is Protestants who claim they are good enough to be saved whenever they decide. 

Catholicism and the world are shoulder to shoulder in preaching this message from Satan that sinners can begood enough.

On the contrary. And that is easy to prove. Ask a Catholic if they are saved. The answer, "I don't know. God is my Judge." Now ask a Protestant the same question. "Of course!" They will brag and boast! "I have my faith!!! I am saved! Thank God I'm not like the Catholics and all those other people of the world!!!" Now, lets read the Scripture and see who is truly saved:

Luke 18:9-11

King James Version (KJV)
⁹ And he spake this parable unto certain which trusted in themselves that they were righteous, and despised others:
¹⁰ Two men went up into the temple to pray; the one a Pharisee, and the other a publican.
¹¹ The Pharisee stood and prayed thus with himself, God, I thank thee, that I am not as other men are, extortioners, unjust, adulterers, or even as this publican.

That is the Protestant attitude.

Now, Protestants always wonder why we kneel before God in Church. Here's why:¹³ And the publican, standing afar off, would not lift up so much as his eyes unto heaven, but smote upon his breast, saying, God be merciful to me a sinner.
¹⁴ I tell you, this man went down to his house justified rather than the other: for every one that exalteth himself shall be abased; and he that humbleth himself shall be exalted.

Sincerely,

De Maria