Why is it that the Christians of the first century were able to do so much damage, in a positive sense, in a relatively short period of time? How did those first-century believers, without tools such as the printing press, radio, television, and the Internet, still radically impact their culture?

In short, they followed and practiced a Christianity not known by many today. We might read about it in the book of Acts and classify it as something radical, over the top, and a bit on the extreme side. But to them, it would have been nothing less than ordinary Christian living. If we want to impact our world like the first-century believers did, then we need to return to the principles they applied, starting with the Christianity they practiced.

Let's take a look at five earmarks of authentic Christianity, taken from 1 John.

First, an authentic Christian confesses Jesus Christ as Lord (1 John 4:15). Christianity must begin with a verbal acknowledgment of Jesus Christ as the Lord of your life. The Bible says that even the demons believe and tremble (James 2:19). True Christians should be able to say that Jesus Christ is their Lord.

Second, if you are a true Christian, you will be unhappy or miserable when you're sinning (1 John 3:9). This doesn't mean you will never sin if you are a Christian (1 John 1:8). But there is a difference between recognizing that we will fail in some way, shape, or form in the future and going on a willful, continual track of sin. If you really are a child of God, you will have a sense of discomfort when you sin, because you know in your heart of hearts that what you are doing is wrong.

Third, an authentic Christian enjoys fellowship with other believers (1 John 5:1). A true Christian will want to be around other Christians. Those who isolate themselves from other believers do so at their own peril, because the Bible tells us that it is important to get together, encourage one another, and correct one another (Hebrews 10:24-25). After all, why should God go to your house if you won't go to His? A lot of us want all of the fringe benefits of Christianity without applying ourselves.

Fourth, an authentic Christian obeys the commands of Jesus Christ. If you are a true believer, then you will obey the commands of Jesus Christ (1 John 5:3). I will not deny that the Bible is filled with so-called rules, but their purpose is not to make our lives miserable. Rather, they protect us from potential harm. The person who blatantly and continually breaks the commandments of God simply does not know Him.

Finally, an authentic Christian loves and obeys the Word of God (1 John 2:5). You cannot effectively live the Christian life without a love for, and obedience to, God's Word. All true disciples of Jesus Christ will be students of Scripture and will walk according to its teaching. This is vital to authentic Christian living, because the Bible is indeed the very textbook of life (2 Timothy 3:16). Yet so many believers will not read the Bible. They don't realize that success or failure in the Christian life depends on how much of the Bible they get into their hearts and minds on a regular basis. We have to do it.

These are the earmarks of authentic Christianity, according to God's Word. Yet it seems today that authentic Christianity is at an all-time low. In a poll George Barna conducted about the impact of Christianity on society, he concluded, "Christianity is having a minimal influence on thoughts, words, and deeds of people under the age of 40." His examination of 100 indicators of attitudes, beliefs, and behaviors showed that Christians are very similar to non-Christians in their everyday behavior. Barna observed, "Non-Christians expect Christians to differ in the religious realm."

I would add that Christians should differ from non-Christians in every realm, not only the religious realm. We should differ not just because we show up in church on Sunday or at a midweek Bible study. We should conduct our businesses differently, treat our husbands and wives differently, and raise our children differently. We should live differently, according to different values. If we are going to turn our world upside down for Christ today, then people need to see authentic Christianity.