Can a true Christian fall away?

Why give warnings if our salvation is secure?

The great 19th Century preacher Charles Spurgeon put it like this:

God preserves his children from falling away; but he keeps them by the use of means; and one of these is, the terrors of the law, showing them what would happen if they were to fall away. There is a deep precipice: what is the best way to keep any one from going down there? Why, to tell him that if he did he would inevitably be dashed to pieces ... So God says, ‘My child, if you fall over this precipice you will be dashed to pieces.’ What does the child do? He says, ‘Father, keep me; hold thou me up, and I shall be safe.’

Heb. 6:4 For in the case of those who have once been enlightened and have tasted of the heavenly gift and have been made partakers of the Holy Spirit, 

Heb. 6:5 and have tasted the good word of God and the powers of the age to come, 

Heb. 6:6 and then have fallen away, it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame. 

Heb. 6:7 For ground that drinks the rain which often falls on it and brings forth vegetation useful to those for whose sake it is also tilled, receives a blessing from God; 

Heb. 6:8 but if it yields thorns and thistles, it is worthless and close to being cursed, and it ends up being burned.

Jesus has promised that He "will never leave thee, nor forsake thee." (Hebrews 13:5) Paul assures us that "He who has begun a good work in you will complete it until the day of Jesus Christ." (Philippians 1:6) Friends, we need to believe these promises! Having faith that Jesus can save us is what the gospel is all about. Listen to what John wrote about this: "These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life, and that you may continue to believe in the name of the Son of God." (1 John 5:13) This is wonderful news, wouldn't you say?

God does not merely command us to begin to believe for a time, and then fall away. He requires us to continue to believe until the end, living lives of repentance and covenant faithfulness. Granted, He does not ask for a perfect faith, but He does ask for a real faith, one that produces real, lasting change.

 Colossians 1:21-23 

And you, who were once alienated and enemies in your mind by wicked works, even now hath He reconciled, in the body of His flesh through death, to present you holy and unblamable and unreprovable in His sight,if ye continue grounded and settled in the faith, and be not moved away from the hope of the Gospel, which ye have heard and which was preached to every creature under heaven, of which I, Paul, am made a minister.
 1 John 3:3-6 

And every man that hath this hope in Him purifieth himself,�?®even as He is pure,Whosoever committeth sin transgresseth also the law, for sin is the transgression of the law.And ye know that He was manifested to take away our sins, and in Him is no sin.Whosoever abideth in Him sinneth not; whosoever sinneth hath not seen Him, neither known Him.
Hebrews 12:1 . Therefore, seeing we also are compassed about by so great a cloud of witnesses, let us lay aside every weight, and the sin which doth so easily beset us, and let us run with patience the race that is set before us,

We will persevere because God preserves us. God will keep us from falling—not one will be lost of all those who belong to the Son. True believers are not able to leave Christ, for Christ is at work within them.

 John 10:28-29 And I give unto them eternal life, and they shall never perish, neither shall any man pluck them out of My hand.My Father, who gave them to Me, is greater than all; and no man is able to pluck them out of My Father's hand.

 Philippians 1:4-6

always in my every prayer for you all making request with joy, for your fellowship in the Gospel from the first day until now,being confident of this very thing, that He who hath begun a good work in you will perform it until the Day of Jesus Christ.
Philippians 2:12-13 

Therefore, my beloved, as ye have always obeyed, not only in my presence, but now much more in my absence, work out your own salvation with fear and trembling. For it is God who worketh in you, both to will and to do of His good pleasure.

First of all, it's important to understand that God will never give up on someone who has accepted Jesus Christ as their savior. The Lord says in John 10:27-29 "My sheep hear My voice, and I know them, and they follow Me. And I give them eternal life, and they shall never perish; neither shall anyone snatch them out of My hand. My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of My Father's hand."