The importance for Christians to hold the line, that we are born for spiritual combat comes from the Vicar of Christ, Pope Leo XIII (1810 - 1903):
"To recoil before an enemy, or to keep silence when from all sides such clamors are raised against truth, is the part of a man either devoid of character or who entertains doubt as truth of what he professes to believe. The only ones who win when Christians stay "quiet" are the enemies of truth. The silence of Catholics is particularly disturbing because frequently a few bold words would have vanquished the false ideas."
Pope Leo XIII is very clear the importance of giving witness to the truth! Jesus said that He is the "Way, the Truth, and the Life"! That truth is not subject to the human will, but is the height the human will reaches towards. St. Peter gives this explanation:
There is a story about Pope St. Pius X (1835 - 1914, successor to Pope Leo XIII) when one day he was talking to a group of his Cardinals, he posed this question to them:
What is the need today to save society?
The group of Cardinals began to deliberate this question, one responded, "Build Catholic Schools", another one cried out, "build more churches", and yet another answered "speed up the recruiting of priests". Pope St. Pius X took the opportunity to say:
"No, the most necessary thing of all at this time, is for every parish to posses a group of laymen who will be at the same time virtuous, enlightened, resolute truly apostolic".