What is the biggest threat faced by the church today? Many in the U.S. seem to think the answer is government tyranny. Tyranny is always a danger, but tyranny is not the biggest threat faced by the church in the U.S. or any other nation. Historically, there have been many times when the church has lived under tyranny, and sometimes the church has even grown (numerically as well as spiritually) as a result. We should remember that the entire New Testament was written when the church was a small persecuted community living under the tyranny of Rome.
I am not suggesting that we should play down the seriousness of tyranny. Many of our brothers and sisters around the world are currently suffering under various forms of tyranny and persecution. Their suffering is real. Those of us who are able should do what we can to help.
That said, we need to remember that other people, even those in political power, can only hurt our bodies (Matt. 10:28). They can't kill the soul. If we allow Scripture, rather than click-bait headlines, to shape our answers to the big questions, we will realize that the biggest threat to the church is not something external. The biggest threat is something within. The biggest threat to the church has always been unrepentant sin - grumbling (Exod. 15:24), idolatry (Exod. 20:3), apostasy (Exod. 32), and such.
God's people in the Old Testament faced all manner of external persecution at various times and places, but such persecution is not what brought Israel low. Israel was brought down by her idolatry and apostasy (see any of the prophetic books). Tyranny and persecution were, more often than not, divine punishments for Israel's covenant breaking sins. These things were written for our instruction (1 Cor. 10:11), and we should take heed.
Political tyrants cannot destroy the church. The very gates of hell cannot prevail against the church (Matt. 16:18). But what is a threat to the church? What can result in Christ removing a church's lampstand (Rev. 2:5)? The same threats that existed in the Old Testament - idolatry, apostasy, faithlessness, false doctrine, tolerating false doctrine. In short, the biggest danger the church faces is sin. The biggest danger the church faces comes from the hearts of those within the church.
How do we guard against this threat? There have always been those who think the best way to protect the church from sin is to get away from all the sinners. Go out into the desert all alone. Build a monastery. Don't smoke, drink, or chew, and don't hang out with those who do. The one fundamental truth all such approaches fail to remember is that we can't get away from sin by getting away from sinners because we are not sinless yet, and we can't get away from ourselves. We can't get away from our own hearts.
We can only guard against this threat to the church by dealing with the sin in our own hearts. Sin is the greatest tyrant. Sin is the greatest enslaver. Sin is what tears individuals and churches apart because sin is inherently satanic. The sins of the world are significant, but when professing Christians are so caught up with what those outside are saying and doing that they aren't taking their own sins seriously, they become the greatest threat to the church.