Sometimes it seems that those who support traditional Christianity have been backed into a corner. People claim that, given a little while, our faith will totally pass away. Now the Bible claims that God is in control of the world (Ephesians 1:11; Romans 8:28; Isaiah 43:13) and those who trust in Him will be ultimately be victorious (2 Corinthians 2:14; Romans 8:37; 1 John 5:4,5). But does that really fit with what we see in the world?
When the Roman Empire fell it was overrun by peoples who were pagans or whose beliefs did not fit in with orthodox Christianity (they believed that Jesus was not God, but just the highest created being). Also, much of the Christianity of the Empire was more of a cultural Christianity, with no deep convictions. Then a man named Patrick went back to the Irish, who had enslaved him, to tell them the truth of God. Later a man named Gregory sent an expedition to preach God's Word to the Anglo-Saxons.These people were converted and send missionaries to others and stirred up the lackadaisical Christianity back on the continent. And the situation turned around.
In the middle of the Middle Ages the Christian church was in a sorry state. It had been politicized, and the rulers put their relatives and supporters in positions of leadership in the church organization. These were often uneducated and immoral and farmed out their duties to equally unqualified minions. Further, there was an influx of Greek philosophy that threatened Christian beliefs. But individuals such as Bernard of Clairvaux, Francis of Assisi, and Thomas Aquinas rose to advocate a return to serious, orthodox Christianity. (I cannot endorse all the theology of these men, but they stood against greater error.) At the time of the Renaissance the leaders of the church organization had become totally corrupt, being greedy for money and embracing an immoral lifestyle. Also, once again Greek philosophy was coming back as a competitor to Christianity. Then the Protestant Reformation was started by Martin Luther to restore Christian truth and curb abuses. In the Enlightenment it looked like secularism and watered-down Christianity were going to triumph. But men like John and Charles Wesley and George Whitefield started the revival movement to counteract it. (None of these movements was perfect, and each brought their own new problems, but the pattern of God's deliverance continues.)
Since then we have had various movements and controversies, but while it sometimes has been on the ropes, historic Christianity always bounces back. I grew up in the sixties, when we were worried about Communism taking over the world, with worldwide persecution of the Faith. But while it is still around, Communism is not doing so well since 1989. Now I do not want to promise anything specific, as I do not claim to understand God's plan and He often does things differently than we might expect. But we should not despair, but continue working for God's truth, knowing He is still in control.