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.
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.
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].
27 Whoever does not bear his own cross and come after me cannot be my disciple [a true Christian].
33 So therefore, any one of you who does not renounce all that he has cannot be my disciple [a true Christian].
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.