Much of the New Testament was written against the backdrop of the lure of false religion. For example, in the early years of Christianity, shortly after Paul and Barnabas first travelled to the southern part of the province of Galatia, where churches were established in the cities of Pisidian Antioch, Iconium, Lystra, and Derbe (Acts 13:14 - 14:23); there was trouble when they returned to Antioch of Syria (Acts 15:1). Shortly after, apostles, elders, and brothers dealt with the corrupt influence of Judaizing Christians, first in Jerusalem and then back in Antioch of Syria (Acts 15:2-35). Paul went to Galatia again (Acts 16: 1-6) accompanied by Silas. They clearly established the corrective decisions that had been made in Jerusalem (verse 4). Nevertheless, the controversy persisted, and eventually it threatened the young Christian groups of Galatia. In the letter to the Galatians, Paul's rebukes could not have been stronger! The adding of Old Covenant requirements, as if they were necessary for salvation, did not enhance the gospel; this legalistic scheme perverted the gospel! It arrogantly distorted the truth of God's grace by which He alone is glorified. Furthermore, such errors divided Christians with the inflated idea that certain ones could boast or glory due to their performance of legal works. This led to an atmosphere of outrageous peer pressure (Galatians 2:11-14) to the end that some feared eating with Gentile Christians!
Later in the first century, the perils of counterfeit spirituality were modified by Greek thinking. For example, Paul's stern refutation of errors in the letter to the Colossians showed the existence of a strange mix of Jewish-rooted legalism regarding food, drink, a festival, a new moon, or a Sabbath day (2:16), and other worldly influences: namely, philosophy (2:8), worshipping angels (2:18), elementary principles of the world (2:20), and "self-abasement and severe treatment of the body" (2:23). The letter of First Timothy warned against the upcoming influence of deceitful spirits and doctrines of demons by which people would hypocritically forbid marriage and would also insist on abstaining from foods that God intended as a blessing to be thankfully enjoyed (4:1-5). The context referred to the danger of "falsely called 'knowledge' − which some have professed and thus gone astray from the faith" (6: 20b, 21).
By the time the letter of First John was written, a sprouting network of bogus gnosis (knowledge or wisdom) needed to be combated to distinguish genuine Christianity from "falsely called knowledge." What had developed eventually became distinctly identified as Gnosticism, exclusive religion masquerading as the true Christian faith. This erroneous system was profoundly rooted in dualism, the view that matter itself was inherently evil and thus not created by God. Only invisible "spirit" was considered to be of value. This overt despising of the material world and even of the human body was in extreme contradiction to God's estimation of the creation as "very good" (Genesis 1:31). This counterfeit "knowledge" led to two divergent trends. Asceticism was the deliberate neglect of the body through starving it, advocating the strict shunning of many basic needs or physical enjoyments. The opposite Gnostic extreme was antinomianism, the total indulgence of bodily appetites without regard to any moral standards. This approach was based on the logic that, since evil bodies could not be reformed, mere "physical" lack of restraint meant nothing. This warped attitude by hijacking the Christian concept of grace led to the idea that careless or deliberate sinning was not a big deal. Why not give into sinful urges in order to usher in more grace? Of course, Paul had already refuted such twisted reasoning in Romans 6:1, 2.
Whereas early errors had underestimated Christ's redemptive efficacy, the latter Gnostic mindset offered skewed views about the identity of Jesus himself. According to perverse thinking patterns, if bodies were evil by nature, how could the Son of God really have been human? This line of thought produced Docetism, the belief that Jesus only seemed to be a man. This perception of a nebulous Jesus led to denying that Jesus really died as a flesh and blood human being. It further muddled the reality that he was bodily raised from the dead by God, since bodies themselves were deemed to be bad. Consequently, many Gospel truths were savagely compromised by the rise of Gnostic deceptions.
Also, just as the earlier Judaizing influence split Christians by a scenario in which puffed-up elitists, zealous for the Mosaic Law, would look down upon others, so Gnostic thinking was extremely divisive. Adherence to the Gnostic ideal of escaping the evil of the body, a very popular concept among Greek philosophers, became a compulsory focus on intellectualism. As matter itself was disdained, so simple people, not equipped to jump through the secret, "spiritual" hoops of an exclusive group were shamelessly despised. Thus, the total opposite of loving one's brother was fostered by this elaborate, contemptuous worldview!
In contrast to this insidious religion, which was rooted in "falsely called knowledge," the letter of First John weaves a beautiful tapestry of genuine knowledge. Believers did not need to be confused by those who separated themselves from true Christian fellowship (2:18-21). Certain phrases in 1 John abound: "by this we know" (repeated in 2:3, 5; 4:6, 13; and 5:2), "by this you know" (4:2) − along with similar expressions like: "from this we know", "that you may know", "we have come to know", "we know love by this", and "we will know by this"; in addition there are constant repetitions of "we know" and "you know." These are not meaningless redundancies! This flourishing string of "know" phrases highlights the wonderfully interwoven threads of known Biblical faith against the dark currents of pretended "knowledge."
Some essential facets of bonafide Christianity revealed in connection with "by this we know" wording comprise bold proofs concerning what a real Christian walk looks like. A true believer who loves God is committed to keeping God's commandments, His Word, as Jesus did. This is the only way to really know that we know God (2:3-6 and 5:2). It includes moving away from darkness into light by producing righteous actions. Such practice is coupled with simple honesty to deal with the sins that have been committed. A humble, godly response to the magnanimous effect of Jesus' blood sacrifice requires renouncing sins, confessing them to God, and moving away from them. It does not mean frivolously ignoring them, denying them, or deliberately continuing to practice them (1:5-2:2; and 3:4-10). (Those influenced by Gnosticism were prone, on one hand, to take sins lightly or, conversely, to twist the concept of avoiding sins into ritualistic, self-imposed, harsh rules on the body.) Obeying God's Word is further developed with specific exhortations to love one's brother, whereas failing to love people is equated with being a murderer! We can know we are in the truth only if our love is proactive, not a hollow theory of mere words (3:10-24; and 4:7-21). The proof of real love stands in stark contrast to the prideful stance of an esoteric club in which someone, obsessed with himself, might boast of "loving God" while carelessly disregarding others!
These vibrant fibers of the tapestry are strongly woven in the bedrock confession that Jesus, the Son of God, came as a real flesh and blood man. (4:2 and chapter 5.) Denial of Jesus' humanity, in whatever convoluted form, does not come from God's spiritual influence! Such denial absolutely comes from an influence of "antichrist" - a false spirituality that is against Christ (4:3). (Remember 1 Timothy had warned people of the advent of "doctrines of demons.") Another closely associated proof of real Christianity is willingness to listen (4:6) to all these straightforward gospel declarations, instead of haughtily assuming that one "knows" better! A final factor, specifically connected to the phrase "by this we know", is the truth that we have been given "of His spirit" (4:13). True Christians have the testimony within, the real spiritual guidance regarding Jesus' identity as a man (5:6-10). Confidence in being anointed so as to continue in what God's spirit has clearly revealed keeps one alert regarding any deceptions coming from those who deny Jesus as the human Messiah. By abiding in the anointing of holy spirit, one perceives that denial of the real Jesus is also a denial of God as the Father (2:18-29).
In conclusion, despite how darkened thinking continues to misrepresent Christian realities, the solid proofs prevail! Being devoted to loving God by keeping His commandments and loving others with real compassionate involvement keeps us walking in the light. Believing in Jesus as the unique Son of God, while being completely convinced of his manhood, keeps us on track and in fellowship with the Father. Humbly listening to all these biblical truths, while staying confident in the guidance of holy spirit, yields the fruit of simple, godly living. "By this we know."