Who’s a real Christian and who’s not? Who’s faithful to the teaching of Christ and who’s selective in following him? Who’s morally committed and who’s not?

Everywhere, in the name of religion, truth, morality, ideology, or political-correctness, we’re erecting various tests of orthodoxy and morals. Usually one issue of morality, dogma, dress, or political- correctness is set up as the litmus test. How you stand on that issue determines how you are judged in general and, depending whether you’re liberal or conservative, that issue can be anything from abortion, to feminism, to gay marriage, to war, to poverty, to capital punishment, to clerical dress, to (inside of Islam) whether not a woman covers her face in public. But, invariably, there is a litmus test, one issue on which you are judged.

So it’s worth asking: Did Jesus have a litmus test? Is there one issue, principle, or dogma within his teaching that can function as a criterion for judgement so that we are, in effect, a Christian or not, depending upon where we stand on that issue?

The question isn’t a simple one: On the one hand, it asks the question of essentials: What’s essential and what’s negotiable in the teachings of Jesus? But it asks, as well, whether there is there any one thing inside the teachings of Jesus that can serve as a defining criterion as to what makes one uniquely Christian?

Regarding the question of essentials, I submit, that there are four things that Jesus asks of anyone who would be his disciple:

First, that he or she “keep the commandments”, both the larger commandment of the heart “to love God and neighbour” and the ten commandments. “If anyone loves me, he will keep my word.” An essential component of Christian discipleship is having a private relationship to Jesus and being faithful in the area of private morality.

Second, Jesus mandates social justice as non-negotiable, not optional, within Christian discipleship. This is clear from Jesus’ own life, from the text on the last judgement in Matthew’s gospel, and from the fact that in the gospels, on average, one out of every eight lines is an imperative from Jesus to reach out to the poor.

Third, as Jesus defines it, discipleship demands involvement within a concrete community of faith. Christian discipleship is not something we do alone. We’re asked to journey to God with each other, as part of an ecclesial community, as part of a church. As the First Epistle of John, puts it: “The one who claims to love a God that he cannot see and does not love a neighbour whom he can see is a liar.”

Finally, what Jesus asks of us as an essential component of discipleship is a mellow, warm, grateful heart. Discipleship isn’t just about what we do; it’s also about the spirit within which we do it. We need the right truth, but also the right energy. Nothing counts for much, no matter how right or orthodox the action, if it doesn’t issue from love and gratitude. In T.S. Eliot’s words: “The last temptation that’s the greatest treason, is to do the right thing for the wrong reason.” When our concern for truth, orthodoxy, justice, or morality comes out of a place of anger, bitterness, or judgement, we are no longer acting as disciples of Jesus, no matter how right the cause. No action rooted in bitterness, anger, jealousy, self-righteousness, or in a desire for revenge can ever justify itself in Jesus’ name.

Thus these things – private integrity, social justice, involvement in ecclesial community, and mellowness of heart – are the essentials of Christian discipleship. But there’s still a further question: Is there anything in Jesus’ teaching and his challenge to us that might serve as a litmus test? Is there any one, singular, teaching that can serve as a criterion as to who is and who isn’t a true disciple of Jesus?

There is. For Jesus, the litmus test for a disciple, at least for a mature disciple, is this: Can you love an enemy? Can you bless someone who curses you? Can you forgive, and can you forgive even a murderer?

It is precisely to this challenge that Jesus refers when he tells us that our virtue must go deeper than the virtue of the scribes and Pharisees. The scribes and Pharisees were, for the most part, sincere and decent men and women who loved God, tried to help the poor, were concerned about truth and morals, and practised justice. But loving an enemy and forgiving a murderer aren’t prescribed by justice, the ten commandments, church dogma, human decency, or even sincerity. They’re an invitation to something deeper, an invitation that comes from Jesus’ life and teaching, and an invitation that, in the end, constitutes the litmus test of mature discipleship.

Who’s a real Christian and who’s not? The deepest answer in the gospels would be: The person who can love an enemy, bless those who curse her, and forgive everyone, even a murderer.