What is the earliest use of the word “Christianity”?

When did the word “Christianity” actually come into use?  The Greek is Χριστιανισμός.

A certain amount of searching online brought me to an Italian article,^[1] from which I learned that the first person to use the word is none other than Ignatius of Antioch.  There are 4 references, in Ignatius’ letters to the Magnesians 10,1 and 3;  Romans 3,3;  and Philadelphians 6,1.

Let’s see what he says!  The Greek is from the TLG, the translation is Lake’s Loeb, the links are to the ANF.  Note that the ANF translation online for each chapter gives first the original (“short”) text, and then the “long” text as interpolated in the 4th century by the Apollinarist heretics.  We’re quoting here the original.

Magnesians c. 10:

Ἄτοπόν ἐστιν, Ἰησοῦν Χριστὸν λαλεῖν καὶ ἰουδαΐζειν. Ὁ γὰρ Χριστιανισμὸς οὐκ εἰς Ἰουδαϊσμὸν ἐπίστευσεν, ἀλλ’ Ἰουδαϊσμὸς εἰς Χριστιανισμόν, εἰς ὃν πᾶσα γλῶσσα πιστεύσασα εἰς θεὸν συνήχθη.

3. It is monstrous to talk of Jesus Christ and to practise Judaism. For Christianity did not base its faith on Judaism, but Judaism on Christianity, and every tongue believing on God was brought together in it.

Romans c.3:

Ὁ γὰρ θεὸς ἡμῶν Ἰησοῦς Χριςτὸς ἐν πατρὶ ὢν μᾶλλον φαίνεται. Οὐ πεισμονῆς τὸ ἔργον, ἀλλὰ μεγέθους ἐστὶν ὁ Χριστιανισμός, ὅταν μισῆται ὑπὸ κόσμου.

3. Nothing visible is good, for our God, Jesus Christ, being now in the Father, is the more plainly visible. Christianity is not the work of persuasiveness, but of greatness, when it is hated by the world.

Philadelphians 6:  (Strangely the ANF renders “Christianity” as “Christian doctrine”)

[Unable to locate the Greek!]

1. But if anyone interpret Judaism to you do not listen to him; for it is better to hear Christianity from the circumcised than Judaism from the uncircumcised. But both of them, unless they speak of Jesus Christ, are to me tombstones and sepulchres of the dead, on whom only the names of men are written.

The word Χριστιανισμ** appears in Ignatius, the Martyrdom of Polycarp, Clement of Alexandria, and Origen before the council of Nicaea, and then entirely in post-Nicene writers.

1. ^[1]Enrico Norelli, “Χριστιανισμός e Χριστιανός in Ignazio di Antiochia e la cronologia delle sue lettere”, in M. B. Durante Mangoni ; D. Garribba ; M. Vitelli (ed.), Gesù e la storia. Percorsi sulle origini del cristianesimo, Trapani, Il Pozzo di Giacobbe , 2015, 171-189.  Online here.  Note that the Greek is given in a non-unicode font in the article.↩