While doing some sermon research for my sermon on Philippians 3:2-15 this weekend I came across these words from Pastor John MacArthur. They are from a sermon Pastor MacArthur preached entitled, "The Distinctive Qualities of the True Christian." (I am responsible for the highlighting.)
And so, again we come back to this very familiar biblical theme. It is all through the New Testament, the theme of true Christianity. Who is the true child of God? In fact, I would venture to say that there are two dominant themes in the New Testament apart from the exaltation of Christ Himself who is the theme of all of the Word of God. The first theme in the New Testament is a presentation and elucidation of the gospel.
But there is a secondary theme that runs right behind that first one and it is the matter of who is a true Christian. Having delineated the gospel in great clarity, it is then of great importance that one ascertain whether or not in fact he or she is a true Christian. That theme is also abundant in Scripture. In 2 Corinthians, Paul says, "Examine yourselves whether you be in the faith." Once the faith has been delineated the key is to know whether you're in it. Jesus said in Matthew 7 that in the last time many will come and say, "Lord, Lord, but He will confess to them, I have never known you, depart from Me you workers of iniquity." So there are some who will think they are Christians and children of God, who think they belong inside the covenant and the Kingdom but who are sadly mistaken. That too is a theme.
It starts with Jesus confronting the false faith of the Pharisees and the religious leaders of Israel. It moves to Peter exposing the false faith of Simon. It moves then to Paul who warns of the false faith of the Judaizers who want to demand people observe the law and be circumcised before they can be saved. It moves then to James who describes the dead faith of a fruitless life. And then it moves to Jude who squares off against the hidden phonies in the church. And finally it comes to John who records the description of a church that had a name but had no life, it thought it was alive but in fact it was dead. And everywhere in between all of those high points, the theme of true Christianity runs like a unbroken thread through the fabric of the New Testament.