I would like to know what the difference is between a "fake" Christian and a "real" Christian?
No one here has yet referenced Scripture in answering your question. I find this so odd. Here's what God in His Word has to say:
Isaiah 29:13
13 Therefore the Lord said: "Inasmuch as these people draw near with their mouths And honor Me with their lips, But have removed their hearts far from Me, And their fear toward Me is taught by the commandment of men,
Although it is Isaiah the prophet speaking here, he is actually prophesying of the time of Christ and the hypocrisy of the Pharisees. In any case, the definition of hypocrisy is given here. Whether it was a Jew in Christ's time or a "Christian" today, the essential nature of hypocrisy as Isaiah described it so long ago has not changed. When you ask about "fake Christians" you are essentially asking about hypocrisy. Isaiah answers your question by pointing to a disparity between an individual's words and the attitude of the individual's heart as a basic indicator of "fakeness" or hypocrisy.
Matthew 15:6-9
6 then he need not honor his father or mother.' Thus you have made the commandment of God of no effect by your tradition.
7 Hypocrites! Well did Isaiah prophesy about you, saying:
8 'These people draw near to Me with their mouth, And honor Me with their lips, But their heart is far from Me.
9 And in vain they worship Me, Teaching as doctrines the commandments of men.' "
Christ echoes Isaiah here, using the prophet's definition of hypocrisy as his own. At the core of a "fake Christian" there is a contradiction between what they say and the attitude of their heart.
Matthew 7:13-27
13 "Enter by the narrow gate; for wide is the gate and broad is the way that leads to destruction, and there are many who go in by it.
14 Because narrow is the gate and difficult is the way which leads to life, and there are few who find it.
15 "Beware of false prophets, who come to you in sheep's clothing, but inwardly they are ravenous wolves.
16 You will know them by their fruits. Do men gather grapes from thornbushes or figs from thistles?
17 Even so, every good tree bears good fruit, but a bad tree bears bad fruit.
18 A good tree cannot bear bad fruit, nor can a bad tree bear good fruit.
19 Every tree that does not bear good fruit is cut down and thrown into the fire.
20 Therefore by their fruits you will know them.
21 "Not everyone who says to Me, 'Lord, Lord,' shall enter the kingdom of heaven, but he who does the will of My Father in heaven.
22 Many will say to Me in that day, 'Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?'
23 And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness!'
24 "Therefore whoever hears these sayings of Mine, and does them, I will liken him to a wise man who built his house on the rock:
25 and the rain descended, the floods came, and the winds blew and beat on that house; and it did not fall, for it was founded on the rock.
26 But everyone who hears these sayings of Mine, and does not do them, will be like a foolish man who built his house on the sand:
27 and the rain descended, the floods came, and the winds blew and beat on that house; and it fell. And great was its fall."
In this passage Christ identifies those who are truly his own by the "fruit" they bear. Outward conformity is not enough. Obedience to God arising from a sincere desire of the heart is what separates the false prophet from the true one, the foolish man from the wise one, and the true Christian from the fake one.
James 4:4
4 Adulterers and adulteresses! Do you not know that friendship with the world is enmity with God? Whoever therefore wants to be a friend of the world makes himself an enemy of God.
Fake Christians usually give themselves away here. They are easy and comfortable with the world's values, morals and goals. As a result, they are quick to defend worldliness within themselves and the church. I've seen entire churches move toward a model of functioning where the unbelieving "seeker" is catered to by the church through an adoption of the world's character. In one extreme instance, I attended a church where the special music during the service was given by a peroxide blonde in a blood-red tube dress who sang a Sass Jordan song! I can tell you the men in the audience weren't thinking about the glory and holiness of God while this curvaceous young woman was strutting her stuff on stage! Anyway, this kind of accommodation of the world, as James explains, makes people who profess faith in Christ the enemy of God.
Luke 9:59-62
59 Then He said to another, "Follow Me." But he said, "Lord, let me first go and bury my father."
60 Jesus said to him, "Let the dead bury their own dead, but you go and preach the kingdom of God."
61 And another also said, "Lord, I will follow You, but let me first go and bid them farewell who are at my house."
62 But Jesus said to him, "No one, having put his hand to the plow, and looking back, is fit for the kingdom of God."
Fake Christians are the ones who believe they are saved when they haven't ever submitted all they are, and possess, and desire to Christ. Jesus is fifth, or tenth, or twentieth place in their list of priorities. Instead of being the hub around which life revolves, the center of decision-making and thought, he is an addition, an accessory to living, like furniture or life insurance.
Luke 14:25-33
25 Now great multitudes went with Him. And He turned and said to them,
26 "If anyone comes to Me and does not hate his father and mother, wife and children, brothers and sisters, yes, and his own life also, he cannot be My disciple.
27 And whoever does not bear his cross and come after Me cannot be My disciple.
28 For which of you, intending to build a tower, does not sit down first and count the cost, whether he has enough to finish it--
29 lest, after he has laid the foundation, and is not able to finish, all who see it begin to mock him,
30 saying, 'This man began to build and was not able to finish.'
31 Or what king, going to make war against another king, does not sit down first and consider whether he is able with ten thousand to meet him who comes against him with twenty thousand?
32 Or else, while the other is still a great way off, he sends a delegation and asks conditions of peace.
33 So likewise, whoever of you does not forsake all that he has cannot be My disciple.
Self-sacrifice - actually, the
death of Self - is a fundamental requirement of walking with Christ, of being his follower. Fake Christians have never understood this. All their piety and outward righteousness are merely a means of gratifying Self. Love of Christ does not motivate obedience. Instead, being seen to be a good person, being applauded for one's good deeds, being able to pat oneself on the back are what motivates a fake Christian's "righteous" living. Real Christianity puts Self to death and in its place the life of Christ is instituted. Fake Christians do not "die daily" as the apostle Paul did and as Christ in the above passage says his true followers must.
Titus 1:15-16
15 To the pure all things are pure, but to those who are defiled and unbelieving nothing is pure; but even their mind and conscience are defiled.
16 They profess to know God, but in works they deny Him, being abominable, disobedient, and disqualified for every good work.
Again, fake Christians "profess to know God" with their mouths but inwardly and in their actions are "abominable, disobedient, and disqualified..."
Selah.