Some Scriptures to Consider
Matthew 13:20-21 (ESV)
20 As for what was sown on rocky ground, this is the one who hears the word and immediately receives it with joy, 21 yet he has no root in himself, but endures for a while, and when tribulation or persecution arises on account of the word, immediately he falls away.
Matthew 24:6-14 (ESV)
6 And you will hear of wars and rumors of wars. See that you are not alarmed, for this must take place, but the end is not yet. 7 For nation will rise against nation, and kingdom against kingdom, and there will be famines and earthquakes in various places. 8 All these are but the beginning of the birth pains.
9 “Then they will deliver you up to tribulation and put you to death, and you will be hated by all nations for my name's sake. 10 And then many will fall away and betray one another and hate one another. 11 And many false prophets will arise and lead many astray. 12 And because lawlessness will be increased, the love of many will grow cold. 13 But the one who endures to the end will be saved. 14 And this gospel of the kingdom will be proclaimed throughout the whole world as a testimony to all nations, and then the end will come.
Matthew 10:31-33 (ESV)
31 Fear not, therefore; you are of more value than many sparrows. 32 So everyone who acknowledges me before men, I also will acknowledge before my Father who is in heaven, 33 but whoever denies me before men, I also will deny before my Father who is in heaven.
Matthew 7:21-23 (ESV)
21 “Not everyone who says to me, ‘Lord, Lord,’ will enter the kingdom of heaven, but the one who does the will of my Father who is in heaven. 22 On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ 23 And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’
Matthew 25:31-46 (ESV)
31 “When the Son of Man comes in his glory, and all the angels with him, then he will sit on his glorious throne. 32 Before him will be gathered all the nations, and he will separate people one from another as a shepherd separates the sheep from the goats. 33 And he will place the sheep on his right, but the goats on the left. 34 Then the King will say to those on his right, ‘Come, you who are blessed by my Father, inherit the kingdom prepared for you from the foundation of the world. 35 For I was hungry and you gave me food, I was thirsty and you gave me drink, I was a stranger and you welcomed me, 36 I was naked and you clothed me, I was sick and you visited me, I was in prison and you came to me.’ 37 Then the righteous will answer him, saying, ‘Lord, when did we see you hungry and feed you, or thirsty and give you drink? 38 And when did we see you a stranger and welcome you, or naked and clothe you? 39 And when did we see you sick or in prison and visit you?’ 40 And the King will answer them, ‘Truly, I say to you, as you did it to one of the least of these my brothers, you did it to me.’
41 “Then he will say to those on his left, ‘Depart from me, you cursed, into the eternal fire prepared for the devil and his angels. 42 For I was hungry and you gave me no food, I was thirsty and you gave me no drink, 43 I was a stranger and you did not welcome me, naked and you did not clothe me, sick and in prison and you did not visit me.’ 44 Then they also will answer, saying, ‘Lord, when did we see you hungry or thirsty or a stranger or naked or sick or in prison, and did not minister to you?’ 45 Then he will answer them, saying, ‘Truly, I say to you, as you did not do it to one of the least of these, you did not do it to me.’ 46 And these will go away into eternal punishment, but the righteous into eternal life.”
Matthew 3:8 (ESV)
Bear fruit in keeping with repentance.
Hebrews 6:1-6 (NET)
1 Therefore we must progress beyond the elementary instructions about Christ and move on to maturity, not laying this foundation again: repentance from dead works and faith in God, 2 teaching about baptisms, laying on of hands, resurrection of the dead, and eternal judgment. 3 And this is what we intend to do, if God permits. 4 For it is impossible in the case of those who have once been enlightened, tasted the heavenly gift, become partakers of the Holy Spirit, 5 tasted the good word of God and the miracles of the coming age, 6 and then have committed apostasy, to renew them again to repentance, since they are crucifying the Son of God for themselves all over again and holding him up to contempt.
2 Peter 1:3-11 (ESV)
3 His divine power has granted to us all things that pertain to life and godliness, through the knowledge of him who called us to his own glory and excellence, 4 by which he has granted to us his precious and very great promises, so that through them you may become partakers of the divine nature, having escaped from the corruption that is in the world because of sinful desire. 5 For this very reason, make every effort to supplement your faith with virtue, and virtue with knowledge, 6 and knowledge with self-control, and self-control with steadfastness, and steadfastness with godliness, 7 and godliness with brotherly affection, and brotherly affection with love. 8 For if these qualities are yours and are increasing, they keep you from being ineffective or unfruitful in the knowledge of our Lord Jesus Christ. 9 For whoever lacks these qualities is so nearsighted that he is blind, having forgotten that he was cleansed from his former sins. 10 Therefore, brothers, be all the more diligent to confirm your calling and election, for if you practice these qualities you will never fall. 11 For in this way there will be richly provided for you an entrance into the eternal kingdom of our Lord and Savior Jesus Christ.
1 Timothy 4:1 (ESV)
Now the Spirit expressly says that in later times some will depart from the faith by devoting themselves to deceitful spirits and teachings of demons
1 Timothy 6:20-21 (ESV)
20 O Timothy, guard the deposit entrusted to you. Avoid the irreverent babble and contradictions of what is falsely called “knowledge,” 21 for by professing it some have swerved from the faith. Grace be with you.
Luke 2:13-14 (ESV)
13 And suddenly there was with the angel a multitude of the heavenly host praising God and saying,
14 “Glory to God in the highest,
and on earth peace among those with whom he is pleased!”
Luke 14:26 (ESV)
26 If anyone comes to me and does not hate his own father and mother and wife and children and brothers and sisters, yes, and even his own life, he cannot be my disciple [a true Christian].
He who wishes to follow Him must choose Him so unconditionally as Lord and Guide that he makes all other loyalties and ties absolutely subordinate to his loyalty and devotion to Him. The Saviour, of course, does not mean that he who desires to follow Him must hate his parents and other loved ones as such, but certainly if loyalty to Him clashes with loyalty to them he is to treat his loved ones in this condition as though they are persons whom he hates. But even when he acts thus towards them for the sake of his absolute loyalty to Christ, he must continue to love them and all other people, in accordance with Christ's law of love.
Norval Geldenhuys. Commentary on the Gospel of Luke. (Grand Rapids, MI: WM. B. Eerdmans Publishing Company, 1951), 398.
Luke 14:27 (ESV)
27 Whoever does not bear his own cross and come after me cannot be my disciple [a true Christian].
Indeed, he who is not willing to die the most hideous death, by crucifixion, for the sake of his love and loyalty to Christ, cannot be His disciple. The general idea that these words of Jesus about "bearing the cross" refer to passive submission to all kinds of afflictions, like disappointments, pain, sickness and grief that come upon man in this life, is totally wrong. The people to whom Jesus spoke those words fully realised that He meant thereby that whosoever desires to follow Him must be willing to hate his own life (verse 26) and even to be crucified by the Roman authorities for the sake of his fidelity to Him. So, in a wider sense this pronouncement of Jesus means that only that person who for the sake of His service surrenders all self-seeking and abandons all striving after his own interests can be His disciple.Norval Geldenhuys. Commentary on the Gospel of Luke. (Grand Rapids, MI: WM. B. Eerdmans Publishing Company, 1951), 398.
Luke 14:33 (ESV)
33 So therefore, any one of you who does not renounce all that he has cannot be my disciple [a true Christian].
Here the Saviour declares expressly what the indispensable requirement is for anyone who whishes to become a real disciple of His. He must relinquish all his possessions - not merely money and material things, but also his dear ones and everything that his heart clings to, yea, even his own life, his own desires, plans, ideals and interests. This does not mean he must sell all his possessions or give away all his money or desert his dear ones and become a hermit or beggar or wanderer, but it means that he must give Christ full control over his whole life with everything that hs is and all that he possesses, and that under His guidance and in His service he should deal with his possessions in a manner that is best. In some cases it has meant, or will mean, that a man will have to take leave of his worldly possessions and go into distant lands to work for Christ. In most cases, however, it means that man in his ordinary life places his all at Christ's disposal to such an extent that, while still remaining in possession of his goods, he honours and serves Him thereby. The important thing is that whosoever desires to follow Him must be inwardly free from worldly-mindedness, covetousness and selfishness and wholly devoted to Him.Norval Geldenhuys. Commentary on the Gospel of Luke. (Grand Rapids, MI: WM. B. Eerdmans Publishing Company, 1951), 398-399.
Jesus used the term disciple but never Christian therefor a true Christian (and not one in name only) will have to be a disciple of Christ as well.
The only condition where this would not be true is for someone who is about to die and will not have time to come under the Lord's discipleship within the body of Christ (Luke 23:39-43). This is something to take into serious consideration because it could imply that if we are not a disciple based on Jesus' own criteria then we are therefore also not a Christian.
I believe God requires us to always be working out our salvation (Phil 2:12), always growing in Christ and becoming more and more like Christ, maturing in Christ (2 Pet 1:3-11). When we stall out or backslide then if we don't, by the grace of God (Luke 15:1-10), turn back to the ongoing process of maturing in our character - becoming more Christ like, which is the process of sanctification, we may cease to be a disciple of Jesus Christ. Fortunately and thankfully, God is faithful even when we are not and once we have made the good confession in all sincerity then God considers us His children and as a good Father He will discipline us in order to turn us back into the narrow way that leads to life.