Here is a trick question for you: How many Christians are there on earth? To answer that question, many people might rush to Pew Research, or pull up census information, or all sorts of official studies done on the global distribution of religions. But there's a problem. Those polls show only one thing: The number of people who claim (or are claimed by their parents in the case of children) to be Christians. That doesn't tell you how many people actually know Jesus.
To really drive this point home, consider a young girl I once knew in college. I was fresh in, and very vocal about my newfound Christian faith, and she was one of many people who would often challenge me about it. "I don't know why you believe that s***", she would shout, ensuring the entire class heard it. And it wasn't just angry and profane ramblings. She had some very challenging objections. Why does God allow some people to die young and others old? Why could God save a murderer in prison who believes in Him, but she herself will be condemned because she does not? She was very anti-Christian, both at an intellectual level, and on an emotional level. Yet, she claimed "I'm a Christian, but I don't believe in God."
Now, should her claim be taken seriously? Given the vehemence with which she argued against Christianity, it makes no sense that she should be numbered among Christians, yet because she was baptised as a baby, she believed she was, and always would be, a Christian. So what would she show up as on a census? What would she answer when a poll asks her religion? This woman, my brethren, is not an outlier. First, she is not the only atheist who calls herself a Christian. There are others out there who believe infant baptism makes you a Christian, and indeed, this is the lie that convinced me as a child of about 6 or 7 to "leave" the faith I was raised in. My friend told me that because I hadn't been Christened, I couldn't be a Christian, and because I obviously didn't know anything at the time, I believed her. But more than that, there are many so-called "Christians" who, while they profess to be Christians, are not saved.
While on Earth, Jesus promised that He would preserve His Church, but He did not promise there would be many of us. Quite the opposite, Jesus warned that the gate and way that lead to destruction is very wide and broad. Many find their way there, but life is found by few.
To really illustrate this, consider the Jews. Israel has a rather muddy history when it comes to sound theology. They often fell into apostasy. During the ministry of Elijah, for example, Israel had almost totally turned to Baal. A mere 7,000 remained faithful to God (1 Kings 19:18; Romans 11:4). 7,000 Jews out of how many? Quite a few. Now, if 7,000 Jews, among a few hundred thousand, is enough for God to claim to have preserved His people, how many true Christians does He need to claim He has preserved His Church? Answer: 2. Only 2 Christians would have to remain on the Earth in order for the Church to be present, because Christ Himself said where 2 or more are gathered in His name, there He is in the midst of them (Matthew 18:20).
Now, obviously, there are significantly more than 2 Christians on earth. And there are certainly more than 7,000. But sadly, the alleged 2 billion Christians is an exaggeration. It is an inflated number due to those who claim the name of Christ, but in their hearts, they are no more faithful than before they received the Gospel. This should serve as both an encouragement and a warning. It should encourage us, because we see many "Christians" falling away, and it can be very disheartening. Why do so many in the Church seem to be becoming very liberal? Why are certain heretical sects so large? Simple: They are on the broad path. So it's not that they're falling away after all. God is keeping His promises. But it should also serve as a warning: Even if we are not necessarily on the broad path, could our teachers be? Let us stand firm on the word of God, studying it prayerfully and faithfully applying it to our lives. Even if false converts were to outnumber the saved a hundred to one, our God still reigns supreme, and all glory will go to Him in the end.