1 John: All Christians and Only Christians Walk in Faith, Obedience, and Love - No Exceptions!

This booklet is included in and comprises one section of my book Physical and Spiritual Salvation: Justification, Sanctification, Glorification, the Messianic Kingdom, & Ezekiel's Temple in Ezekiel 40-48, Matthew, Romans, & 1 John.
John wrote about "the Logos [word, logic] of life" (1 Jn. 1:1), and his method is to use logic. John gives us one formal logic proposition statement after another, often stated both negatively and positively, to prove that "All Christians and only Christians walk in Faith, Obedience, and Love - no exceptions."
John shows it's impossible to be in union with God, which all Christians are, meaning those who have been justified, and not have that result in a walk of faith, obedience, and love. "God is light, and ... no darkness. If we say we have union with him [claim to be a Christian], and walk in darkness, we lie [our claim to be a Christian is false], and we don't do the truth [we aren't Christians]. But if we [claim to have union with him and] walk in the light, as he is in the light, we [demonstrate we] have union [not only with him but also] with one another [our claim is true], and the blood of Jesus Messiah his Son cleanses us from all sin [we are justified, i.e. Christians]," 1 Jn. 1:5-7.
Faith: "If we say, 'We have no sin [i.e. are self righteous],' we deceive ourselves [our claim is false], and the truth is not in us [we aren't Christians]. [But] if we confess we are sinners [trust in God's provision of forgiveness of sin in salvation], he is faithful and just to forgive us our sins [our claim to be forgiven is true], and to cleanse us from all unrighteousness [justification] [we are Christians]," 1 Jn. 1:8-9. 7
Obedience: "He that says, 'I know him [i.e. claims to be a Christian],' and doesn't keep his commandments is a liar [his claim to be a Christian is false], and the truth is not in him [he's not a Christian]. But whoever [claims to know him and] keeps his word, in him truly is the love of God perfected [we are Christians]: hereby know we that we are in him [we are Christians]," 1 Jn. 2:4-5.
Love: "He that says he is in the light [claims to be a Christian], and hates his brother, is in darkness [his claim to be a Christian is false] even until now [he never was a Christian]. He that loves his brother abides in the light [he is a Christian], and there is none occasion of stumbling in him [and will be a Christian forever]," 1 Jn. 2:9-10.
One benefit of understanding this is that we can know who is a Christian, versus just claiming to be a Christian and going to church, etc. "As you have heard that antichrist will come, even now are there many antichrists [all who claim to be Christians but aren't]," 1 Jn. 2:18. "Hereby know we the spirit of truth, and the spirit of error," 1 Jn. 4:6. A second benefit is for our own assurance of salvation. "These things have I written to you that believe on the name of the Son of God; that you may know that you have eternal life," 1 Jn. 5:13.
But the greatest benefit, and the main reason John wrote, was so we would have full joy. "These things we write to you so that your joy can be full," 1 Jn. 1:4. If all Christians always walk in the light, and we know we have believed the gospel and received justification and thus are Christians, then we know we always walk in the light, and that is a tremendous source of joy! Not understanding what we already have will not prevent us from having some joy anyway, since it is one of the fruits of the indwelling Spirit (Gal. 5:22), but only understanding what we have provides full joy.