If we define "Christian" as all the people who have a religion, organization, or a philosophy that they call Christian, then there are a lot of Christians in the world. 

If we define "Christian" as someone who has a relationship with Christ, what Barna Research calls "Born Again," then there are not so many Christians in the world.  That would be the group that the Bible described as the "Chosen."   Many are called and few are chosen. 

If we define "Christian" as a Christ-one, someone who has a very intimate relationship with Jesus who is filled with the Holy Spirit, constantly led by the Holy Spirit, and obedient to keep step with the Holy Spirit, then there are very few Christians indeed.  There are very few who are flowing with the love that can only come from the throne of God and who are not living a double life, half Christian and half ungodly.  This is a remnant.  Keep in mind that God has almost always worked with a remnant.  During the dark ages, it became illegal not to be a "Christian."  There were many hypocrites and only a remnant who were following Christ.  In America, there are many who attend church services, but only a remnant are following Christ.  Many are called and few are chosen.  Even fewer are found faithful.   
 
Among Christians, there are varying levels of maturity.  Some are walking toward God, but that is a very small remnant.  There are many nominal (in name only) Christians.  That won't get a person anywhere with God because God cannot be fooled. 

There are many who just belong to a Church because it is a source of contacts for their business. Churches are also inexpensive social clubs.  They are places where lukewarm Christians can go for activities and they will usually be accepted and treated with respect.  An churchy organization may just be a place where religious people who have no relationship with Jesus can go to feel religious and better than other people.  There are many who are just pretending to believe so that they don't get pressure from their parents or relatives.

In all of this, there is a small remnant who actually hear and understand what God is saying.  They have a real and living relationship with Jesus.  They can sense Jesus guiding their lives in a very personal way.

It quickly becomes obvious that no one has fulfilled this calling completely.  There is a coming day when the work will be completed, at least in a remnant.  The Bible calls it "the Manifestation of the Sons of God," and also, "the Adoption, which is the Redemption of our Bodies."  This is also referred to as "the First Resurrection."  In Ephesians, it is stated this way:

Ephesians 4:11 And he gave some, apostles; and some, prophets; and some, evangelists; and some, pastors and teachers; 4:12 For the perfecting of the saints, for the work of the ministry, for the edifying of the body of Christ: 4:13 Till we all come in the unity of the faith, and of the knowledge of the Son of God, to a perfect man, to the measure of the stature of the fulness of Christ: 4:14 That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive; 4:15 But speaking the truth in love, may grow up into him in all things, which is the head, even Christ: 4:16 From whom the whole body fitly joined together and compacted by that which every joint supplies, according to the effectual working in the measure of every part, makes increase of the body to the edifying of itself in love.

In understanding Ephesians 4:12-16, you must go back to the main verb, edoken, in verse 11.  Christ gave the gifts.  He gave the office of apostle.  He gave the four ministries.  Those gifts are not the persons but the Christ in those persons, as another passage says, "Christ in us, the hope of glory."  The text cannot be read any other way than to understand that these gifts are performing all of this work as the gifts proceed from Christ.  Grace means, literally, free gift.  This is grace, and we know from Scripture that it is grace that does any work that is done.  In fact, God could give no greater gift, so He gave us of Himself.  He chooses to do it through apostles, ones sent.  He chooses to not use those who send themselves or who are sent by men.  It is plain from the Greek that it is not gifted people who do any of this work, but rather the Gift Himself does the work through the members.  This is true whether it is the apostle who is totally equipping and completing the member or the member who is now also moving in the power and authority of the same gift.  When any member comes into submission to the apostle, that person carries the same anointing and authority of the apostle just as long and to the extent that they are in submission.  They are not submitting to a man but to Christ Himself.  If you can discern the Body of Christ, you will see this.  If you see this, flesh and blood has not revealed this to you, but your Father in Heaven has revealed it.