As far as the average layperson needs to understand, anyone who dies without sacramental baptism and membership in the Church will indeed go to Hell. Invincible ignorance is a marginal and 'sideline' issue that the Novus Ordo keeps bringing up in order to justify their refusal to evangelize and catechize. The definition of someone who can rightly be called invincibly ignorant grows more and more narrow every single day. While I accept totally and unreservedly the teaching of the Church that those IN invincible ignorace MAY be saved, the doctrine is:
1) first, only applicable to people in geographic and socio-political situations we cannot even begin to imagine
2) NEVER to be used as an attempt to justify a failure to preach the Faith to all nations
based upon a knowledge that is possessed by God Almighty ALONE and was NEVER intended to be a definition by which men may pass judgment upon the final destinies of unknown and unreached people groups.
No one can be called invincibly ignorant if they have had even the barest of truths about Christ told or shown to them. If you tell me there's a bag of money waiting at the bank for me, and I laugh and refuse to go, it matters not what I believe. If that bag exists and I do not go retrieve it, I lose its benefit no matter how briefly I considered the validity of your claim.
To clarify, a person may be validly baptized and thus become, sacramentally, a member of the Church. However, a refusal of that person to VISIBLY and INTENTIONALLY ENTER that Church in Whom is the sole source of sanctifying grace and salvation IS for that baptized person to fall into grave mortal sin and thus be Hell-bound.
In short, a person who knows they need to BE baptized has no excuse as to the claims of the Roman Catholic Church to be the ONE true Church of Jesus Christ. If a person understands a need for Christian baptism, they must understand the existence of 'a' church. If they understand the existence of 'a' church, then they are without excuse as to the existence of at least a CLAIM of being 'THE' Church, by some one, or some several, visible or invisible organizations.
If, then, a person can know and should know of at least the CLAIM of one or several organizations to the title of 'THE' church, then they are without excuse as to their duty to examine those claims and be joined to THE Church, which is WITHOUT QUESTION the Roman Catholic Church, outside of which no one may be saved.
All you need to understand about 'outside the Church there is no salvation' is this:
that God the Father Almighty, in His fullness and omnipotence, has ordained that there is only ONE Savior and Mediator between God and man, He being Jesus Christ, God the Son. Jesus Christ founded the ONE Church within which dwells His Sacramental, sanctifying grace which is absolutely necessary for salvation.
If, then, God gave only ONE Savior, and His graces come ONLY through ONE Church, it stands to reason that God's power and desire to save can only be understood NORMALLY as THROUGH the agency of His Church. Anyone who is saved BY GOD WITHOUT THE NORMAL AGENCY OF HIS VISIBLE CHURCH is STILL saved BY GOD and thus can be said to be saved WITHIN the Church, though not VISIBLY, because the Church derives Her power to sanctify and save FROM GOD. The agency of God as Savior and the agency of Church as repository of saving grace are one and the same, because God did not establish two or any other number of churches but ONE. Thus, the Kingdom of God EQUALS (does not SUBSIST IN, BUT ACTUALLY IS) the Roman Catholic Church, and the Roman Catholic Church EQUALS (does not REPRESENT, BUT ACTUALLY IS) the Kingdom of God.
Did that make sense to you, friend?