Which of the following characteristics do you think most fundamentally distinguishes humans one from another? Is the population most clearly divided by the young and the old (age or maturity)? Is it by male and female (gender)? Is society divided along economic lines (the rich and the poor)? Is it divided on moral lines (the just and the unjust, or the lawful and the unlawful)? Is it divided along relational lines (the married and the single or divorced or widowed)? Or is it divided along educational lines (the literate and the illiterate or the college educated and the uneducated)? Or perhaps along lines of affiliation and preference (Democrats and Republicans, Gators and Seminoles, those who like country music and those who are sane)?
Murray Harris in his excellent theological book "Slave of Christ" explores this issue through Paul's eyes as it truly exists and ought to exist in the mind of every follower of Christ. “No longer did Paul see the ‘slave-free’ or the ‘Jewish-Gentile’ or the ‘male-female’ antithesis as of fundamental importance in any categorizing of humanity. Their place was taken by the ‘in Christ’ – ‘separated from Christ’ antithesis (Eph 2:12-13; cf. Rom 9:3).”
Every Christian has been set free from the slavery of sin and made new in Christ. The only distinction that matters eternally is "in Christ" and "not in Christ." John 3:36 also states this fundamental distinction, "Whoever believes in the Son has eternal life, but whoever rejects the Son will not see life, for God's wrath remains on him."
What difference does this make on a daily basis? Christians must seek to relegate former distinctions to an area of far lower priority than the fundamental and axiomatic distinction: follower or rebel. This fundamental distinction must then prioritize our efforts with others: we are either walking together as followers or prayerfully reaching out to one still in need of rescue. Thus, when we meet someone, this ought to be one of the first things we seek to establish, so we know how we can rightly pray for and befriend that person.
Is there anyone you know who you can rattle off a series of facts and earthly characteristics to distinguish that person, but whose eternal destiny you remain unaware? The simple challenge is to refocus on our friends' and coworkers' relationship with Christ. If I can't say whether my friend is a Christian or not, I must determine when I will find out, and have the guts to love him enough to ask plainly what he believes about the Son of God.