Corpus Inscriptionum Latinarum XI 2547a (Chiusi, 3rd century A.D.) =
Inscriptiones Latinae Christianae Veteres 900 (vol. I, p. 168, "Clusii in coemeterio Catharinae"; my translation):
So long as you shall live, man, live; for after death there is nothing. All things stay behind, and man is this which you see.
dum vibes, homo, vibe; nam post mortem nihil est. omnia remanent et hoc est homo quod vides.
Richmond Lattimore,
Themes in Greek and Latin Epitaphs (1935; rpt. Urbana: University of Illinois Press, 1962), p. 320:
[T]he Christianity and the antiquity of this last have alike
been doubted.
Lattimore's remark is just a copy of Ernst Diehl,
ILCV, loc. cit.:
sunt qui ut de homine christiano tituli auctore, ita de tituli ipsius origine antiqua iure dubitent.
Cf. Martial
1.15 and
8.44.1-2.