ISIS has threatened again and again to wipe out Christianity. Our times are not unlike the times of the Early Church, when Christians were literally thrown to the lions for their beliefs. Rather than let themselves be wiped out, Christians instead became stronger. They internalized their faith and practiced in private. In that way, they kept the faith alive.
Some folks mistakenly think that this feast refers to our Lord - that he was immaculately conceived, without stain of sin. Well, that's true, but that's what the Annunciation is all about, not the Immaculate Conception. The Solemnity of the Immaculate Conception refers to the conception of the Blessed Virgin Mary, who was conceived without original sin.