The necessity for salvation of belonging to the Church is a necessity of means. And whereas invincible ignorance excuses from guilt, it does not supply the want of a necessary means. Those who failed to clamber aboard Noah’s Ark were all drowned in the Flood, irrespective of whether this failure was due to invincible ignorance or not. Does it follow that God will punish by deprival of salvation those who were guilty of no sin by their failure to join the Church? It does not. Anyone who is invincibly ignorant of the duty to enter the Church, but faithfully obeys the dictates of conscience, will receive the supernatural enlightenment necessary to enable him to make an act of supernatural faith. If he co-operates with actual grace by making this act, he can proceed to the act of hope and the act of charity, thereby acquiring the state of sanctifying grace - supernatural life. In this case he is united with the Catholic Church by desire (which remains partly implicit), for by faith he believes whatever God has revealed (even if he knows very little of what that revelation contains) and by charity he desires to accomplish the will of God (though he does not realise that this implies joining the Catholic Church.)