Expectation of salvation for the poorly catechized The Catholic Church teaches in the Catechism on Baptism that there are several types of Baptism, one of which is for those fellow eternal-soul-endowed humans who have never heard of Christ. 

But, what does the Church say about those who have heard of Jesus; know a little bit of what the Church teaches;  received validly all the sacraments of initiation; but then, because what they know (or think they know) was so shoddily taught they wholly reject every lick of the Catholic Church in favor of Buddhism, Islam or Atheism because they never remotely understood what they had in the Church since it was presented in such an ineffective manner*. 

Are they apostates or can we apply the logic, "to whom much is given, much is expected", to posit that this person was given nothing so nothing is expected? 

* I'm looking for Catholic doctrine, not criticism of my straw man, I think he or she is the best kind of person. Who, actively seeking the truth was presented with none by a wall of bad Catechesis in the Catholic Church.  As a kid, I had very little notion of a global church and nearly never went to any parish except my home one.  I could have easily been this person having only understood the Church through the easily forgotten texts used during Religious Ed. class had it not been for my mom and one excellent priest.
I believe this concern is explicitly addressed in Lumen Gentium - Chapter 2, paragraph 16:


  Finally, those who have not yet received the Gospel are related in various ways to the people of God. In the first place we must recall the people to whom the testament and the promises were given and from whom Christ was born according to the flesh. On account of their fathers this people remains most dear to God, for God does not repent of the gifts He makes nor of the calls He issues. But the plan of salvation also includes those who acknowledge the Creator. In the first place amongst these there are the Mohammedans, who, professing to hold the faith of Abraham, along with us adore the one and merciful God, who on the last day will judge mankind. Nor is God far distant from those who in shadows and images seek the unknown God, for it is He who gives to all men life and breath and all things, and as Saviour wills that all men be saved. Those also can attain to salvation who through no fault of their own do not know the Gospel of Christ or His Church, yet sincerely seek God and moved by grace strive by their deeds to do His will as it is known to them through the dictates of conscience. Nor does Divine Providence deny the helps necessary for salvation to those who, without blame on their part, have not yet arrived at an explicit knowledge of God and with His grace strive to live a good life. Whatever good or truth is found amongst them is looked upon by the Church as a preparation for the Gospel. She knows that it is given by Him who enlightens all men so that they may finally have life. But often men, deceived by the Evil One, have become vain in their reasonings and have exchanged the truth of God for a lie, serving the creature rather than the  Creator. Or some there are who, living and dying in this world without God, are exposed to final despair. Wherefore to promote the glory of God and procure the salvation of all of these, and mindful of the command of the Lord, "Preach the Gospel to every creature", the Church fosters the missions with care and attention.


I think we'd only consider an explicit choice to deny God, properly understood (though never fully understood), as a truly damning sin.

Now, we couldn't claim that every atheist, Buddhist, Muslim, or whatever is engaged in a sincere quest for truth. But, those that are engaged in sincere truth-seeking (and conformance) are headed in the right direction.

But, this does not relieve our obligation, nor should it relieve our desire, to deliver the truth as we know it, with all due respect -- and tact! It is much easier to lose interest in the quest for truth, or become perverse in that quest, if one is not actually presented with the truth! (in charity)