A Dictionary of Early Christian Biography 
Lactantius (1) Lucius Caelius (or Caecilius) Firmianus a well-known Christian apologist of the beginning of the 4th cent.: "Rhetor erat ille non theologus: neque inter ecclesiae doctores locum unquam obtinuit," as bp. Bull says of him (Del. Fid. Nic. ii. 14 4 and iii. 10 20). Lactantius enumerating previous Christian apologists seems only conscious of threeâ€”Minucius Felix Tertullian and St. Cyprianâ€”but this is explained by supposing that he limits himself to his countrymen viz. African apologists. St. Jerome mentions an Itinerary written by him in hexameter verse of his route from Africa to Nicomedia as though he were then leaving home for the first time. The African church produced as did no other country a succession of learned advocates or rhetoricians men of the world who embraced Christianity from conviction and wrote vigorously in its defence culminating in St. Augustine each employing Latin with the freedom of a vernacular and in the case of Lactantius with so much purity as to have procured for him the title of the Christian Cicero; while Italy produced no Christian apologists and till St. Ambrose no great theologian. Divines and men of letters as well as emperors had to be sought in the provinces. In all his empire Constantine could find no better preceptor for his eldest son Crispus then destined to succeed him at Rome than this African Latin. This brought him to Gaul c. 313 the first date we can fix in his career on any tangible grounds. Lactantius had previously been invited to set up a school of rhetoric at Nicomedia. There doubtless he was converted on witnessing the superhuman constancy displayed by the Christians and by his "best beloved" Donatus in particular on whose sufferings in the tenth and savagest persecution under Diocletian he dwells with so much tenderness (de Morte Persecut. cc. 16 35 and 52). Donatus he tells us himself had lain in prison six years when the edict of Galerius published a.d. 311 procured his release. In Gaul Lactantius died perhaps in the year of the Nicene council a.d. 325. To judge from his extant writings he must have been somewhat austere soured it may be by failures as he had no mean estimate of his own powers (de Opif. Dei c. 1; Inst. v. 1â€“4): a man of few and warm rather than of many friends; thoughtful learned conscientious and pure. Eusebius (Chron. a.d. 319) speaks of him as having always been so poor as frequently to have lacked the necessaries of life. St. Jerome says it was his ill-success in getting pupils at Nicomedia from its being a Greek city that induced him to write. St. Jerome gives a list of his writings but whether in the order in which they were published or not he omits to say. The first he names is the Symposium which he calls a youthful performance; the second is the Itinerary; the third the Grammarian. Then comes the well-known treatise de IrÃ¢ Dei still extant which St. Jerome calls pulcherrimum; next his Institutions in seven books extant also on which his fame principally rests; next his own epitome of the same work In Libro uno acephalo ("a compendium of the last three books only," as Cave explains it; but the first half was claimed by Pfaff to have been recovered a.d. 1712 from a Turin MS. and its genuineness though disputed is still maintained). The seventh work named by St. Jerome was in two books addressed to Asclepiades; both are now lost. The eighth which had disappeared also was claimed by Baluze as recovered by him; it was published in 1679 at the commencement of his second book of Miscellanies but with the title Liber ad Donatum Confessorem de Mortibus Persecutorum instead of de Persecutione Liber unus which is that of St. Jerome. Judged by its contents the first is the more accurate title. His four books of letters to Probus two to Severus and two to his pupil Demetrian which St. Jerome regards as eight consecutive books (in Gal_2:4) are lost. The twelfth and last work assigned to him by St. Jerome is de Opificio Dei vel Formatione Hominis. The tract de Morte Persecutorum ends with the joint edict of Licinius and Constantine published at Nicomedia by the former a.d. 313 at which the author lays down his pen in celebrating the triumph of God with thankful joy and prayers day and night for its continuance. He could not have written thus after the differences between Licinius and Constantine had commenced and the former joined the ranks of the persecutors; he therefore probably published it when leaving Nicomedia for Gaul. The first chapter of his tract de Opificio Dei shews it to have been written after probably only just after his conversion and "Quam minime sim quietus et in summis necessitatibus" are just the words that might have been wrung from a recent convert in a heathen capital where Christians were having to choose daily between death and their faith and his old pupils were leaving him on learning what he had become. Supposing Lactantius to have been converted about midway in the persecution under Diocletian at Nicomedia and then betaken himself to writing penuriÃ¢ discipulorum as St. Jerome says there was abundance of time for the composition of all his extant works during the rest of his abode there with the exception of his Epitome. His Epitome and the confessedly later insertions in his Institutionsâ€”e.g. his appeals to Constantine (i. 1 ii. 1 vii. 26) his mention of the Arians and of the Catholic church his promise of a separate work on heresies (iv. 30) which it would seem he never fulfilledâ€”would all naturally fall within the period of his removal to Gaul and tutorship to the heir-apparent to whom he could have scarce failed to dedicate any fresh work had such been afterwards written. Was he the pupil or hearer of Arnobius in his younger days that St. Jerome makes him in one place (de Vir. Illust. c. 80) or contemporary with Arnobius as we might infer from another (Chron. a.d. 326)? There is nothing in their works to connect them and at the commencement of his fifth book in specifying ex iis qui mihi noti sunt (c. 1) those who had written against the assailants of Christianity previously to himself he could scarcely have passed over the work of Arnobius if already published and still less if Arnobius besides being an African had been his old preceptor. We therefore prefer following St. Jerome in his continuation of Eusebius and making Lactantius and Arnobius independent: Lactantius possibly the older of the two. Eusebius finds a place for Lactantius in his Chronicon but none for his supposed master. The work of Arnobius is limited to a refutation of the polytheism of the day and the popular objections to Christianity; that of Lactantius like the City of God by St. Augustine which cites Lactantius with approval (xviii. 23) first exposes the false religions but also expounds the true. It has been analysed by Cave briefly (Hist. Lit. i. 162) by Le Nourry thoroughly (ap. Migne Patr. Lat. vi. 825) by Dupin with his accustomed vivacity (E. H. vol. i. 185â€“187 Eng. trans. by W. W.) and by Mountain (Summary of the Writings of Lactantius i. 129). It is trans. in full with notes in the Ante-Nicene Lib. (T. & T. Clark).
The tract de Opificio Dei may challenge comparison with Cicero's de NaturÃ¢ Deorum in point of style and is far superior to it in depth and originality. The tract de IrÃ¢ Dei , against the Epicureans and Stoics, is intended to prove God as capable of anger as of compassion and mercy. The tract de Morte Persecutorum is a collection of historical facts tending to show that all the emperors who persecuted the Christians died miserably, and may be compared with Spelman's de non Temerandis Ecclesiis of modern times.
As for his theology, the indulgence should be shewn him that all breakers of new ground may claim. Tertullian was the model that he looked up to most: and no writer had as yet eclipsed Origen. His account of the origin of all things ( Inst. ii. 9) reminds us of the speeches of Raphael and Abdiel in Paradise Lost (v. 577 and 808). We cannot read his latest exposition of the Incarnation ( Epit. c. 43) without discovering in it some well-known phrases of the Athanasian Creedâ€” e.g. "The same person is the Son of God and of man, for He was twice born: first of God in the Spirit before the origin of the world; and afterwards in the flesh of man, in the reign of Augustus." Dupin, after having expatiated on his many merits, sums up very justly: "He is accused of doubting whether the Holy Ghost was the third Person, and to have sometimes confounded him with the Son, and sometimes with the Father; but it may be alleged in his defence that he meant nothing else but that the name of the Spirit in Scripture is common to the Father and the Son. But whatever the matter is, we find no footsteps of this error in any of his works, what are now remaining; though in some places he takes occasion to speak of the Holy Ghost. He seems to be of opinion that the Word was generated in time; but it is an easy matter to give a Catholic sense to that expression, as we have seen it done to others: and we may be with justice allowed to do so, since he plainly establishes the Divinity of the Word in that very place."
For further particulars see besides authorities already cited, Le Nourry ( Apparat, ad Bibl. Max. Vet. Pat. t. ii. diss. 3), Fabricius ( Bibl. Lat. lib. xi.), Oudin ( de Script. Eccl. t. i. p. 307), Lardner ( Cred. pt. ii. bk. i. c. 65), Schramm ( Anal. Op. SS. Pat. vol. vii. p. 250), Fessler ( Inst. Patrol. vol. i. p. 328), Nouv. Biog. Gen. vol. xxviii. p. 611. See esp. Brandt in Sitzungsberichte der phil.-histor. Klasse der Kgl. Akud der Wissensh. (Vienna, 1889â€“1891), cxviii.â€“cxxv.
The Nuttall Encyclopedia 
A Christian apologist of the early part of the 14th century, who, from his eloquent advocacy of the Christian faith, was styled the Christian Cicero; he was a pagan born, and by profession a rhetorician.