For by works of the law no human being will be justified in his sight. But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it– the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: for all have sinned and fall short of the glory of God, and are justified by his grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by his blood, to be received by faith. This was to show God’s righteousness, because in his divine forbearance he had passed over former sins. It was to show his righteousness at the present time, so that he might be just and the justifier of the one who has faith in Jesus. -Rom 3:20-26
In many passages, the Bible teaches that God is three persons (Father, Son, and Holy Spirit) in one substance. We cannot make “sense” of this, but God’s ways are higher than ours (Isa. 55:9). He is infinite and we aren’t.
God created the world and everything in it (Gen 1, Acts 17:24). Everything holds together at His word (Heb 1:3, Col 1:16-17). Every breath we take is because he allows and enables it (Acts 17:25, 28).
God created Adam as the first man. Adam represented all of us, similar to how a congressman represents the people of his district. Adam sinned against God and as a result all of his descendants fell into sin with him (Rom 5:12, 19). In some sense we joined in Adam’s sin. It may seem “unfair” to be are punished for what Adam did, but remember that God chose Adam as our representative, and God is perfectly fair and just.
And so our natures are fatally corrupted by Adam’s sin. Our thoughts and desires are evil (Eph 2:1, Rom 3:10-18), and we sin because of it. The news gets worse. God utterly hates sin and cannot stand its presence (Prov 17:15, Rom 2:9-11). One sin is too many (James 2:10, Matt. 5:48) – after all, a single sin by Adam changed the world! God requires the blood of the sinner (his death) because He is just (Zeph 3:5, Ps 89:14, Dt 32:4, Ps 5:4-6, Rom 1:18, Ex. 34:7, etc). He must punish sin with the exact punishment it deserves (Rom 2:5-6, 2 Thess 1:6). That fair sentence is death (Ex. 18:4, Rom 1:32) for the sinner and eternal torment in Hell (2 Thess 1:8-9, Luke 16, etc.). Why? Because God created us and has given us everything. We owe Him perfect obedience. An infinite debt, if unpaid, deserves an infinite penalty.
Again, it’s critical to understand how utterly holy God is. He hates sin and cannot justly permit it by “letting it slide.” God cannot deny Himself. We are completely unpleasing to God on our own (Heb 11:6), and being a “good person” cannot save us, nor can doing “good deeds.” We’re in bad shape because God demands perfection and we are sinners. The puritan Jonathan Edwards was right: we are sinners in the hands of an angry God! Beyond the grave lies the God whom the Bible describes as a “consuming fire” (Heb 12:29), and it is a terrifying thing to fall into His hands (Heb 10:31)! Your worst enemy is nothing compared to Him. Do not be deceived: God’s wrath will fall on those who do not obey Him (John 3:36, Luke 13:3). Jesus warned of Hell and judgment more than anyone else in the Bible, more than a dozen times in the book of Matthew alone.
But there’s good news (the Gospel). In his great mercy, God provides an escape. Jesus Christ, God’s only son, came to earth as a man and perfectly fulfilled the law. He lived a sinless life (Heb 9:14, 1 Pet 1:19) and bore the curse of sin (2 Cor 5:21, Gal 3:13) by dying on the cross as a once-for-all sacrifice ((Heb 10:10, Heb 9:26). Jesus shed His blood for sinners (1 Pet 1:19, 2:24, 3:18), as our substitute (Rom 3:24, Eph 1:7, Col 1:20, Heb 9, etc.). He was the great mediator (Heb 9:15) and peacemaker (2 Cor 5:19) who reconciled God to mankind (Rom 5:1, 9; Eph 1:7, Eph 2:13-16, Col 1:19-20, 1 John 1:7, Rev 5:9, etc.). At the cross, God punishes sin as it deserves and also shows His great love (Rom 3:25-26). Jesus rose from the dead on the third day (1 Cor 15:3-4) after his death. While Adam, our original representative, sinned and brought death to all of his descendants, Jesus becomes the “second Adam” (Rom 5) by rising and offering life to those He represents (Rom 5:17-19, Rom 6:8).
And who does Jesus represent? Those who believe in Him! God commands (Acts 17:30) — not suggests, commands! — that all of us accept His gracious offer by repenting of our sins (Isa. 55:7, Acts 3:19) and believing in Jesus Christ and His resurrection (John 3:16-18, John 5:24, Mark 1:15, Acts 15:11, Acts 16:31, Rom 1:16, Rom 10:9, Heb 7:25, etc). It doesn’t matter what you’ve done or who you are now: ask forgiveness, turn from your sin, and believe. Those who truly believe in Christ and follow Him are “clothed” by the righteousness of God (Rom 3:22, Gal 3:27, Phil 3:8-9). That is, when God looks upon the believer, He sees the perfect righteousness of His Son, our substitute and representative. Through Jesus, we will be able to stand before God on judgment day. As the old hymn says, “Rock of Ages, cleft for me, let me hide myself in Thee.” And it doesn’t stop there. The Holy Spirit lives within us, and God will change us, preparing us for eternal life in glory (John 5:24, John 6:40, Eph 2:7).
A final note: Many claim to be believers simply because they had a “religious experience,” because they prayed a prayer once, or because their parents are believers, or because they were baptized. Those who do this deceive themselves. Self-proclaimed “Christians” often shack up with other Christians, avoid church with a multitude of excuses, and generally live lives no different than unbelievers. Yet the Bible says that Christians are to be “slaves of righteousness” (Rom 6:18), seeking to conform to God’s will as expressed in the Bible, and living transformed lives. The Bible calls us to examine ourselves to be sure that we are do not hear Christ’s awful words: “I never knew you; depart from me” (Matt 7:23). The Christian who sees his own sinfulness in light of the threats and warnings in Scripture will retreat, throughout his life, back to the cross of Christ. Repentance is not a one-time thing. If you are a Christian, you weren’t just “saved,” you are being saved (1 Cor 15:1-2). In all true believers, there is throughout life a gradual growth in holiness (Rom 6:3, Rom 8:28-38), even though we remain sinners until death and actually become more aware of our sinfulness and unworthiness as we grow in our faith. God calls for it and He produces it (Phil 2:12-13). How can the Holy Spirit live in us and we be unchanged? How can God plant a tree that doesn’t bear fruit (Phil 2:13, Eph 2:10, Rom 8:31-39)? How can we be a “new creation” (2 Cor 5:17, Rom 6) and be unchanged? It’s impossible! A constant point in the book of Hebrews is that the saved are those who continue in their faith. Paul tells the Corinthians to “examine yourselves, to see whether you are in the faith” (2 Cor 13:5), following that up with, “Or do you not realize this about yourselves, that Jesus Christ is in you?” In other words, if Christ resides in you, how can that have no effect? Those who think their salvation offers freedom to sin are deceived, because a tree is known by its fruit (Matt 12:33). So, don’t rely on past experience. Repent and seek the Lord. Go to the Cross, remembering his offer of forgiveness and His desire to generously bless. As Rom 6:11 says, “Consider yourselves dead to sin and alive to God in Christ Jesus.” In short, abide in Jesus. Then use the means of grace: Bible reading, prayer, the hearing of the preached word (in church!), and the sacraments (baptism and communion). These are the means the Holy Spirit uses to change and sustain a believer, from the inside out.
Want to learn more? The first stop is the Bible. It is the only infallible source of revelation and the final authority in matters of faith and life. I recommend and use the Reformation Study Bible, which is based on the English Standard Version (ESV) translation. This Bible provides a huge number of notes that provide helpful context and background to verses. The ESV translation is more literal than the NIV and much more readable than the NASB. Second, the ancient ecumenical creeds neatly summarize Christian belief. Third, perhaps the best resources for understanding Christianity and interpreting Scripture — now read by few people, unfortunately — are the historic catechisms and confessions. I subscribe to the Westminster Confession and Catechisms (and here’s a first catechism for children, based on the Westminster Shorter Catechism).
Finally, find and attend a good church! Calvin: “[T]hose to whom he is a Father, the Church must also be a mother.” The Westminster Confession says: “The visible church… is the Kingdom of the Lord Jesus Christ, the house and family of God, out of which there is no ordinary possibility of salvation.”