Justin, 1 Apol. 16:
|And when a certain man came to Him and said, "Good Master," He answered and said, "There is none good but God only, who made all things."||Just then one man approached him and said, "Teacher, what good thing shall I do so that I might have eternal life?" He answered him, "Why do you ask me about what is good? [Only] one is good."|
Notice that the man asks the Matthean Jesus about some "good thing" [τί ἀγαθὸν ποιήσω], whereas according to Justin the man calls Jesus "Good Master." Significantly, in both Mark's and Luke's version of this pericope, the man addresses Jesus as "Good teacher" [διδάσκαλε ἀγαθέ (Mark 10.17; Luke 18.18)] and asks simply, "what shall I do." What's significant here is that Justin, in an extended passage where he seems to be interacting with the Matthean version of Jesus' Sermon, he inserts the Markan and/or Lukan version of a saying found outside the Sermon.1
But that isn't what caught my immediate attention. Rather, notice how Justin—like Christian interpreters ever since—struggles with the balance between ethical rigor and vigorous grace exhibited in the Sermon. Notice that, for Justin, those who commit the sins Jesus discusses in the Sermon become objects of divine judgment: "For not only he who in act commits adultery is rejected by Him, but also he who desires to commit adultery: since not only our works, but also our thoughts, are open before God" (1 Apol. 15). This conflicts rather plainly not only with the picture of Jesus' acceptance of the adulterous woman in the spurious Pericope Adulterae (John 7.53–8.11) but also with the authentically Johannine story of Jesus' encounter with the Samaritan woman at the well in John 4.
But Justin hasn't replaced the merciful, gracious, forgiving Jesus of the gospels with a more rigorous, demanding Jesus (still less a legalistic Jesus!). For in the same paragraph Justin provides a compelling description of the powerful effect of God's grace at work through Christ:
For what shall I say, too, of the countless multitude of those who have reformed intemperate habits, and learned these things? For Christ called not the just nor the chaste to repentance, but the ungodly, and the licentious, and the unjust; His words being, "I came not to call the righteous, but sinners to repentance." For the heavenly Father desires rather the repentance than the punishment of the sinner. (1 Apol. 15)
Immediately afterward Justin cites Matt. 5.46 in support of this portrayal of a gracious and forgiving God. So in very short space we have a picture of God as (i) rejecting not just those who commit sin but also who desire to commit sin, and simultaneously (ii) as calling sinners and accepting their repentance. This tension isn't peculiar to Justin; actually, I think it reproduces fairly accurately a tension found even in the evangelists' accounts of Jesus' Sermon. This shouldn't surprise us; this section of the Apology [viz., 15–17] really isn't much more than an interpretive expansion of excerpts from the Sermon. Actually, this tension between holiness and graciousness lies at the heart of Christian theology itself. And so, nearly nineteen hundred years after Justin Martyr, we still wrestle with the ways the Sermon on the Mount offers comfort to the meek and the mourning without easing the expectation that God's people would be perfect as our heavenly Father is perfect (see Matt. 5.48).
1 Philip Schaff seems not to have noticed this slippage from Matthew to one of the other synoptic gospels; in his footnote here he cites "Matt. xix. 6 [sic], 17." "Why do you call me good?", of course, is precisely what Jesus does not say in Matt. 16.17, because in Matthew the man hasn't called Jesus good!