Muslims might ask why a "security fence" is erected around Islam. To keep Christians from coming in? Get real, Beavis. To make it vvvery difficult to get OUT. Prohibitions like forfeiture of one's life if one converts to the Christian faith are a sure sign of the primitive Sacred.
The Catholic Church, on the other hand, has ever been a refugee camp for runaways from satanic tyrants, a dry beach for the shipwrecked, a field hospital for those wounded by sin. Just GET here anyway you can. You'll enjoy the welcome.