Some Catholics believe that in the long run, Catholics will eventually gain power and influence by sheer force of numbers. Since (on average) practicing Catholics have many more children than non-believers, they argue, practicing Catholics will simply in the long run outbreed non-believers. Therefore, the argument concludes, Catholics simply need to retreat from society and wait for their eventual numerical advantage to kick in.
This argument is dangerously wrong, and fails to take into account three important factors.
The first reason why it fails is numerical. There are far too few Catholic “breeders” to be able to outbreed the general population. If 95-98% of a population is not composed of practicing Catholics (and that is the percentage of Americans who support or practice birth control), that means that the massive percentage of families that have only one child will breed enough children to outnumber their few believing counterparts over one and possibly even two generations. It takes at least two, and more certainly three, generations to outbreed a population. And who knows what will happen in two or three generations?
Also, due to medical advances, people effectively live longer and longer lives. Non-believers will be able to live longer and longer lives, effectively lengthening the process of cultural replacement.
A more telling reason why the demographic argument fails is the fact that the culture of death tends to corrupt. The temptation of risk-free pleasure pushed by the prevailing culture is very strong, and one that young people find difficult to resist. If Catholics are not active in opposing this culture, many of their sons and daughters will be sucked into the vortex of the culture of death. Not all Catholics raised in the Faith remain in the Faith forever!
Finally, and most importantly, “letting people die off” reflects a fundamental misunderstanding of the Church’s mission. As Christians, we cannot let people just remain in their sins. We are called to be missionaries to those in darkness and in the shadow of death. God willing, we are called to bring Christ’s light to all people. We are called to be missionaries to those afflicted by the culture of death, converting by word and example.
So we cannot simply allow non-Catholics to destroy themselves by cultural suicide. We must vocally oppose the evils of those who promote the culture of death, in all its various incarnations, and publicly live the Christian life to the fullest, if we wish Catholicism to thrive for our descendants.