Luke 12:4-5 NKJV
"And I say to you, My friends, do not be afraid of those who kill the body, and after that have no more they can do. But I will show you whom you should fear: Fear Him who, after He has killed, has power to cast into hell; yes, I say to you, fear Him."
This is a sobering text. There are some who think all fear is evil. They will site texts like 1 John 4:18, which tells us that love casts out fear. This is a good teaching, but it is important to gain the proper context. Could it be that there is a good fear, and a bad fear? I think so. Perfect love does cast out fear, except for the fear of God. David said in Psalm 2:11 that we should serve the Lord with fear, and rejoice with trembling. Why? God is to greatly be magnified and glorified, and we should take comfort in His forgiveness and His love. However, with fear, we should serve, knowing that we are not yet in heaven, and just like God cut off Esau from his birthright, He can also cut us off. I believe that the elect is preserved and they are eternally secure, yet, assurance can only be found in the promises of God and His Word. There are many promises that give the believer comfort, and there are many that cause us to be concerned. If you are alive, there is hope. However, rejoice and tremble. Do not presume upon the mercies of God (Romans 2 & 6), and do not give up hope. Be concerned with the glory of God in the life that you have. Be concerned every minute! If you are not concerned and have a false assurance from a verbal commitment made years ago that has not produced any fruit, then you are not a Christian. A Christian grows and bears fruit. Yes, he stumbles, and yes he falls from time to time, but he does not run headlong into sin presuming that God will show him mercy because he signed a card or prayed a prayer at an alter once upon a time. Are you living a lifestyle of lasciviousness? Are you consumed with greed, envy, anger, or lust? Are you ruled by the idols of your own making? Be afraid. Repent and seek God through Jesus Christ. St. Ambrose said that the death of the body is not itself a punishment, but rather it marks the end of earthly punishments (The curse of Adam). The soul continues for eternity, and since God is the judge of the soul, our efforts on earth should be to please Him. Seek Him, confess, repent, and have faith. Pray that God will give it to you! He is just and merciful.