It is my conviction that this verse contains in itself a summary of Christian doctrine. If one wants to understand the whole of Christian doctrine within one concise statement, John 3:36 is it.
John's Gospel is the gospel of belief. Each New Testament Gospel account was written with a specific purpose in mind, and John's was to bring the reader to life-giving faith in Jesus. During John's introduction, sandwiched in between glorious statements about Jesus' identity, John says, "...His own didn't receive him. But to those who did receive Him, who believed in His Name, He gave the right to become children of God, children...born of God" (1:12-13). Towards the end of the Gospel is what can be understood as somewhat of a thesis statement: "These things are written that you may believe that Jesus is the Christ, the Son of God, and that by believing, you may have life in His Name" (20:31). It's clear John wrote in order to bring people to faith in Christ as the Son and Lamb of God "who takes away the sins of the world".
With that being the purpose, the Gospel contains is an inner narrative of faith/belief, almost on every page. All throughout John there are people who believe, then they don't anymore; others believe because of seeing Jesus performing a miracle, but will not accept His hard teaching.
In the same chapter as the most famous verse of all time (3:16), John makes the above statement about believing and obeying to avoid God's wrath. While the whole counsel of God is deep, wide, and full of complexity, there is much simplicity for the one who desires to learn the basic truths of Christian doctrine in the Bible. This verse summarizes it for them.
Justification by Faith: "Whoever believes in the Son has eternal life"
Good news seems a foreign concept to many today. Upon watching the local news, it seems that good news is a thing of the past.
But the Christian Gospel is good news. Jesus Christ is the Savior promised from the Old Testament who came to give his life as a ransom for the sins of many (Mark 10:45), that whosoever believes in Him would have eternal life. His death on the cross matters because He died as a perfect and sinless and innocent man, being the only One who could claim so. What makes it good news is that a relationship with His Father -- the Creator God who will one day bring every deed into judgment and even now judges those who reject Him -- is available freely through Jesus' death and resurrection. Those who stop trying to save themselves by their own performance, trusting in His performance in their stead, are made righteous in God's eyes.
There is no "our part" that is to be played if you trust in Christ. Christ died to give righteousness to believers, and rose to give power and His Holy Spirit to them. When one hopes in Him entirely, there is power and purity that will begin to be recognized in them as they plug into Him as the Vine. It all begins with faith that He will do what He has promised, and that without this truth, no one will make it. Without this conviction, no amount of good works means anything as far as eternity is concerned -- truly, they aren't good at all. "We believe that we will be saved through the grace of the Lord Jesus" (Acts 15:11). He who has brought me to God (1 Peter 3:18) will finish the work He began.
Continual Repentance: "Whoever does not obey the Son shall not see life"
If there be real faith, there must be obedience. As rebirth is a work of God's Spirit through Jesus' resurrection (John 3:3-5, 5:24; Ephesians 2:4-5; 1 Peter 1:3), there has been no real resurrection if obedience to Christ as Lord isn't the product of it. As many have elsewhere said, one can't claim Him as savior without claiming as Lord. I prefer Bonhoeffer's quote: No one has the right to claim that they're justified by faith unless they have left all to follow Him. "Whoever would follow me must deny himself, take up his cross, and follow me" (Mark 8:34). "Whoever loves his life loses it, and whoever hates his life in the world will keep it for eternal life" (John 12:25).
People tend to want to flatten Biblical theology, believing that either we're saved only by faith (saying that we shouldn't even talk about works because it'll make us self-righteous), or that we're saved by faith and works (saying that faith in Christ isn't enough alone but there must also be works). The former typically cite anything from Paul's letters for proof-texts, and the latter typically cite James 2.
But there is no discrepancy for the one willing to think. If we are to be saved, it must be through the death and resurrection of Jesus alone, or else both Testaments wouldn't spend such boundless energy on the importance and sufficiency of Jesus' death and resurrection. Truly what did He accomplish if He doesn't save us? "By His stripes are you healed"; "I lay my life down for my sheep"; "We were reconciled to God by the death of His Son." Since this is received by faith (Romans 3:24), it can't be added to, or it's null (Romans 4:4-5). So then the works and obedience are what flows from the one with faith.
This is all together in keeping with Scripture. Everywhere a heart full of faith produces good works and obedience. God promises in the prophets that obedience will characterize His people because He'll give them His Spirit and a new heart (Ezekiel 36:25-27). Jesus says that evil actions flow from the heart (Mark 7:21-23), while "a good tree produces good fruit" (Matthew 7:17-20). And Paul says that Christians' salvation is "not a result of works, that no one should boast", but rather that we are "Gods workmanship, created in Christ Jesus for good works, which He has already prepared beforehand, that we should walk in them" (Ephesians 2:9-10). Christians aren't saved by what they do, but for new doings which God already has sovereignly prepared for them. He doesn't adopt children from the orphanage because they're his children (they're not -- they're orphans), but so that they'll be His children, simply because of grace.
God Is Not Universal Father: "The wrath of God remains on him"
This salvation is only in light of the fact that man is inherently alienated from God. Though he depends on God for absolutely everything (Psalm 104:27-30; John 3:27), he doesn't acknowledge this. Truly it is because man can't acknowledge what he himself is intent on taking glory for.
Because God is Creator and Provider, He is angry at the world systems that refuse to acknowledge Him as such. But it isn't as though any individual can claim they're innocent because they're subject to a pagan mindset, culture, family, etc. Truly "what can be known about God is plain" to anyone and everyone. And all have rebelled (Romans 3:9-11). Because of this the wrath of God -- condemnation -- is both already experienced (Romans 1:18-24; 1 Thessalonians 2:16) and yet to be experienced in its fullness (Romans 5:9; Ephesians 5:6; 1 Thessalonians 1:10, 5:9).
And Jesus is the Christ who enters into God's creation and lovingly reveals God's truth, that many would be saved. God, though angry at both sin and the sinners committing it, has loved His creation enough to put on a created body and tell His truth in clear language. No one has ever seen God, but Jesus "has made him known" (John 1:18). What can be known about God is now known fully through the Son who called Himself the Truth, saying He came to reveal truth which belongs to His Father. It is all about Jesus, and those who want access to God must come through Him, listening with faithful obedience to His Word. "My words are spirit and life" (John 6:63).
"No one receives His testimony". There have always been very few ready for Jesus' Gospel. Most are distracted, confused, or bored with the things of God. But to those who are ready for Christ, who believe on His Name, He gives the right to become children of God (John 1:12-13). God is not everyone's father (John 8:38), but He is willing that all would be adopted as His children (2 Peter 3:9). If He were already Father to all, we wouldn't need adoption, forgiveness, and grace.
As it is, we start off alienated, and Jesus comes with the truth, bidding us to know Him and His Father. The angry One is also the loving One. This grace is life-giving and paradigm-shattering, but only to those ready to find God's truth in Jesus. And His Word makes ready. May we all bow humbly before it.
