Eternal security is the doctrine that when a person is saved nothing can affect their salvation. They can never lose it for any reason. I believe Eternal Security is true because of the following verses:
John 3:16
For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.
John 6:37-6:40
"All those the Father gives me will come to me, and whoever comes to me I will never drive away. For I have come down from heaven not to do my will but to do the will of him who sent me. And this is the will of him who sent me, that I shall lose none of all those he has given me, but raise them up at the last day. For my Father's will is that everyone who looks to the Son and believes in him shall have eternal life, and I will raise them up at the last day."
John 10:27-29
"My sheep listen to my voice; I know them, and they follow me. I give them eternal life, and they shall never perish; no one will snatch them out of my hand. My Father, who has given them to me, is greater than all; no one can snatch them out of my Father's hand."
Tell me, how can you read those verses and NOT believe in Eternal Security? Jesus is extremely clear. Out of all that the Father gives to Jesus he will lose NONE of them! In other words, Everyone's salvation is Eternally secure! It's right there in black and white! So, what do you think? Is Eternal Security real? Why or why not?
Scripture also warns against apostasy, turning away from Christ, and not shipwrecking our faith.
The question shouldn't then be which set of Scriptures is true, but rather how do we confess all of Scripture?
As a Lutheran I believe that we have complete confidence and assurance in Christ, through faith, on account of the indelible and irrevocable promises of God. I can therefore, because of the Gospel, have every confidence that I am saved, I belong to Christ, and if I am Christ's then I belong to God. And there is nothing which can pluck me from His hand, neither is there any power which can separate me from the love of God which is in Christ Jesus. But that does not mean it is impossible for me to fall away, if I deny my baptism, turn away from Christ, throw away my faith, then I throw away my salvation and become apostate.
If one says, "Well, then you never believed in the first place." Then we deny the confidence and assurance of the Gospel, no longer depending on God's grace and word to hold us and keep us, but rather holding to our own ability.
The problem with Eternal Security, as popularly taught, is that it denies the severe warning in Scripture about falling away and when confronted with the fact of real world apostasy it must attempt to rationalize it away which actually thwarts the assurance and hope of the Gospel. If two people are baptized and have faith in the same Christ, hoping in the same Gospel, and one of them jumps ship and abandons their faith and the other says, "Well they had no faith in the first place, and their baptism was ineffective, and the Gospel did nothing at all" then it denies all confidence in the Gospel and abandons all assurance found in Christ and His Word.
It is only in Christ and His Word that we have this hope, this confidence, this assurance--and we can indeed be confidence and have assurance in Him. That it is, in fact true, that none can pluck us from His hand--because His Word is true and certain and sure. And it is true, certain, and sure even of those who, at some point in their lives, throw it all away to shipwreck their faith--the Word of God is not made null because of the faithlessness of sinful man. The same Gospel falls upon the same soil, that in some cases weeds and thistles grow and choke it out, or birds come and eat the seed, does not make the seed worthless, or the Farmer who sowed that seed ineffective or false.
The apostate has not received a defective Gospel. And it is this same Gospel that we hope and pray will return him back--for we have One who will run to greet the long-lost prodigal. We have a Shepherd who will travel mile over mile over mile to find one lost little lamb.
-CryptoLutheran