A friend told me that:

There are two points that shall be considered:

1 - We have free-will, and our nature, due to the Sin of Adam, tends to do bad things. We are able to do good things because God gives us the actual Grace (a Grace that leads to acting in the right way) _and we accept it_. God always gives His Grace, but it is very easy to say "no" to His Grace.

What makes it easier and what makes it harder to accept God's actual Grace?

- Sinning makes it terribly harder. When we commit a sin, we introduce a disadjustment in our souls and minds. It's like if you threw mud on a glass window; less light would come in. Every sin has this effect, and that is why we shall avoid even venial sins. The more we sin, the easier it is not to accept God-given actual Grace not to sin.

It explains why a thief finds it easier to kill someone than a contemplative nun; he sins more, he sins daily. It is almost impossible for the "light" (taking again the analogy I used above) to come in. God gives the Grace (He always does, even to the worst sinners), but he made himself almost unable to perceive it (this perception of the Actual Grace God gives us is done by our conscience), much less accept it.

A mortal sin has a double effect: he have both a lessening of our ability to accept God's actual Graces (an inner disordering of our souls; that is what Purgatory is about) and a loss of Sanctifying Grace - the Grace that makes us Saints, that purifies us (as contrasted to Actual grace, that will "only" make you able to perform a good deed, Sanctifying grace really makes you better. It sanctifies you - Eastern Catholics would say it "deifies" you).

The loss of Sanctifying Grace (that is the Grace we receive through Baptism), called "eternal consequence of sin", means you are bound to Hell. The ordinary way to receive back Sanctifying Grace is through Confession (although a deathbed perfect contrition will do the same thing, for it will be a perfect desire of Absolution).

- To make it easier to accept actual Grace, on the other hand, we have the Sacraments, specially Holy Communion (Matrimony gives you actual Graces related to the state of married person - not to commit adultery, for instance -, the Holy Orders give you actual Graces related to the state of being a priest - chastity, obedience, etc. - and so on), that will also increase our Sanctifying Grace; prayer, penance and charity (which will, all three of them, as well as Holy Communion, help us getting rid of the disadjustments in our soul, that we call "temporal consequences of sin"; they act like throwing water on the mud that covers the window, coming back to our analogy)

2 - To go to Heaven, you must have Santifying Grace. As I said, it is infused by Baptism and lost by a single mortal sin.

Someone who really follows his conscience and never ever commits a mortal sin (it is possible, although improbable, that it happens) after Baptism will still have Santifying Grace when he dies. A mortal sin is a sin commited consciously and deliberatedly in a grave matter.

Thus it is possible, although improbable, that a Protestant who is very scrupulous about never doing anything he knows is wrong dies without mortal sin. He would have followed what his conscience told him to do all his life long.

Therefore, this person would convert to the True Faith when confronted with intelectual evidence of the Truth, because he has been willing to accept almost all actual Graces God sent him. He would therefore accept the actual Grace of joining the Church.

If, however, this guy is born in the middle of a Protestant country and never ever in his life has the oportunity to know the Truth, he will be a typical case of "invincible ignorance"; he didn't join the Church because he had no way of knowing about Her (that is why the Holy Father, when writing about the sects, told us it is important that clergymen use their distinctive clothing: it will make it easier for this hypotetical "pure-hearted Protestant" to feel and accept the Grace of going to that priest and asking him about the Church, for he would recognize him).

Having explained it, let's go to your question (how can someone who has the Truth fail to verbally provide it if we have a promise from Christ that the Truth is there for us?):

It is easy, and very common. Accepting the Truth means accepting the actual grace of accepting the Truth. It is not an intelectual defeat that will automatically make you accept the Truth.

An intelectual surrender to the Truth will make it harder to conceal its call (for the lies this person had been using to deny the truth will fall down), but as long as this person doesn't want to accept the actual Grace of joining the Church, he won't.

What can be done about it?

Frequent Communion, prayer, penance and charity. The problem is no longer an intelectual one. It is a problem of helping someone to accept Grace. You can use your prayers, your sufferings accepted as penance (or even looked for), the charity you do and the merits of Holy Communion on behalf of your parents.

They won't do it for themselves, but you can do it for them.

Thus you will be slowly cleaning their "window" of our little analogy, and allowing Grace to be more easily perceived by them.

This is cooperating in the work of Redemption.

Be prepared, though. If you really want to help your parents and really asks God to let fall upon you the temporal consequences of their sins (that is what does not allow them to accept the actual Grace of coming home to the Church), you prayers may be granted.

You may get sick, really sick. You may be hated. You may be abandoned by people you love. You may, to put is simply, suffer, and suffer a lot. This suffering will be a gift from God to you. It is the suffering of the re-adjustment of your parents' souls, and borne in the love of God it will bring them to accept the Grace of joining the Church.

Pray for them. Offer your penances, your charities, your merits, your Communion, your prayers on their behalf. And don't argue with them. Show them the Truth, tell them you are praying for them (but do not say you are suffering on their behalf; it could easily be seen as vanity), but never ever raise your voice against them.

After all, there is a gradation between these actions:

1 - Being born in a Protestant milieu and not caring at all about the Truth.

2 - Being born in a Protestant milieu and accepting what is held as Truth by your community, and following it the best way you can (that is, accepting God's actual Grace whenever you perceive it).

3 - Being born in a Protestant milieu and seeking for Truth and asking for divine guidance.

#1 goes to Hell.

#2 goes to Heaven _if,_and_only_if_, he really spends all his lifetime, after receiving a valid Baptism, without doing anything he knows is wrong in a deliberate manner, or if he has a deathbed perfect contrition. Not common and quite hard, but can happen.

#3 finds a Catechism in the trunk of an used car he bought, or meets a deeply religious Catholic person who helps him in the Faith, or accidentaly presses the wrong button on his computer and finds himself in a good Catholic Apologetics page. :)

We must never forget that:

1 - The way to Hell is paved with good intentions and Hell is full of nice people.

2 - How could we know if someone does _only_ what he believes to be God's will for him (lest not to lose Sanctifying Grace?) False security is worse than true fear. Fear of God is a virtue.