But that takes time and wisdom. On the other hand, numerical decline does not automatically signal degeneracy, as the sixth chapter of John's Gospel makes clear. The numbers of persecuted Christians do not always grow. They often shrink, depending on the policies of their persecutors. That does not mean they are apostates, or otherwise deficient in faith.
Demographics are important considerations.
It is more difficult for a parish to grow in a region where the population is static or declining. Many cities and a few states in America have official policies against demographic growth that work against church growth. It can be extremely difficult for a church to add or expand a building in order to accommodate growth. Securing parking is often a major barrier in itself. Cultural changes like the repeal of blue laws, among other things, have forced the churches to compete with Sunday morning commerce, soccer games, marathons, etc.