Once a person truly believes in Jesus Christ, that is, once he repents and places his faith and trust in Christ, he receives Christ into his heart by faith so that the Spirit of God then dwells within him and provides him with the power to live a life that reflects the nature and character of God:
I (Paul) pray that out of his glorious riches he may strengthen you with power through his Spirit in your inner being, so that Christ may dwell in your hearts through faith. Ephesians 3:16-17
Do you not know that your body is a temple of the Holy Spirit, who is in you, whom you have received from God? 1 Corinthians 6:19
You, however, are controlled not by the sinful nature but by the Spirit, if the Spirit of God lives in you. Romans 8:9
For God did not give us a spirit of timidity, but a spirit of power, of love and of self-discipline. 2 Timothy 1:7
Paul continuously labored to build up Christians in their understanding of Christ and the treasures he brings into a believer's heart. He also warned them against being deceived by empty philosophies which exclude Christ.
My purpose is that they may be encouraged in heart and united in love, so that they may have the full riches of complete understanding, in order that they may know the mystery of God, namely, Christ, in whom are hidden all the treasures of wisdom and knowledge. I tell you this so that no one may deceive you by fine-sounding arguments. So then, just as you received Christ Jesus as Lord, continue to live in him, rooted and built up in him, strengthened in the faith as you were taught, and overflowing with thankfulness. See to it that no one takes you captive through hollow and deceptive philosophy, which depends on human tradition and the basic principles of this world rather than on Christ. Colossians 2:2-4,6-8
Having received Christ, how should a person then live? Paul contrasts a life controlled by human nature with a life controlled by the Spirit of God:
The acts of the sinful nature are obvious: sexual immorality, impurity and debauchery; idolatry and witchcraft; hatred, discord, jealousy, fits of rage, selfish ambition, dissensions, factions and envy; drunkenness, orgies, and the like. I warn you, as I did before, that those who live like this will not inherit the kingdom of God. But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control. Galatians 5:19-23
Paul further instructs us:
You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires; to be made new in the attitude of your minds; and to put on the new self, created to be like God in true righteousness and holiness. Be very careful, then, how you live - not as unwise but as wise, making the most of every opportunity, because the days are evil. Therefore do not be foolish, but understand what the Lord's will is. Ephesians 4:22-24; 5:15-17
But now you must rid yourself of all such things as these: anger, rage, malice, slander, and filthy language from your lips. Do not lie to each other, since you have taken off your old self with its practices and have put on the new self, which is being renewed in knowledge in the image of its Creator. Bear with each other and forgive whatever grievances you may have against one another. Forgive as the Lord forgave you. And over all these virtues put on love which binds them all together in perfect unity. Let the peace of Christ rule in your hearts. Let the word of Christ dwell in you richly. Colossians 3:5-10, 13-16
Peter teaches a similar message:
Make every effort to add to your faith goodness; and to goodness, knowledge; and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness; and to godliness, brotherly kindness; and to brotherly kindness, love. For if you possess these qualities in increasing measure, they will keep you from being ineffective and unproductive in your knowledge of our Lord Jesus Christ. 2 Peter 1:5-8
What is the motivation for living this kind of life? It is out of love for God and out of thanksgiving for what God has done for us through Jesus Christ.
For the grace of God that brings salvation has appeared to all men. It teaches us to say "No" to ungodliness and worldly passions, and to live self-controlled, upright and godly lives in this present age, while we wait for the blessed hope - the glorious appearing of our great God and Savior, Jesus Christ, who gave himself for us to redeem us from wickedness and to purify for himself a people that are his very own, eager to do what is good. At one time we too were foolish, disobedient and enslaved by all kinds of passions and pleasures. We lived in malice and envy, being hated and hating one another. But when the kindness and love of God our Savior appeared, he saved us, not because of righteous things we had done, but because of his mercy. He saved us through the washing of rebirth and renewal by the Holy Spirit, whom he poured out on us generously through Jesus Christ our Savior, so that, having been justified by his grace, we might become heirs having the hope of eternal life. Titus 2:11-14; 3:3-7
For Christ's love compels us, because we are convinced that one died for all. And he died for all, that those who live should no longer live for themselves but for him who died for them and was raised again. 2 Corinthians 5:14-15
For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord. Romans 8:38-39
Such should be the life and motivation of the Christian. At times he will surely fall short of the mark, but this is nevertheless what he should strive for, not out of compulsion, but out of love. When he does fall, however, God will cleanse and restore him:
If we claim to be without sin, we deceive ourselves and the truth is not in us. If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness. If we claim we have not sinned, we make him out to be a liar and his word has no place in our lives. 1 John 1:8-10
For the Christian, there can also be great peace in knowing for certain that he will spend eternity in heaven. The Bible says that he can know this for sure. In the book of 1 John, the apostle John teaches many things about the Lord Jesus Christ, and about living a life of absolute trust in him. He concludes his instruction by telling the Christians:
I write these things to you who believe in the name of the Son of God so that you may know that you have eternal life. 1 John 5:13
We have looked at the heart of the gospel and the foundation of true Christianity. Let us now return to the original questions. After death, what then? Do you have the assurance of eternal life with God? If so, what is the basis for your assurance? There is only one foundation upon which we can confidently stand, and that sure foundation is Christ. May you search this matter for yourself and search your own heart. This is the most important matter you must ever face. Your life throughout all eternity depends on whether or not you have been reconciled to God. How will you respond to the call of God? The call of God is to repent and place your trust completely in Jesus Christ. Without him there is no hope. Will you trust him? In the words of the apostle Paul:
We are therefore Christ's ambassadors, as though God were making his appeal through us. We implore you on Christ's behalf: Be reconciled to God. 2 Corinthians 5:20