V. Neri in his article of 1992 does not focus on the omission of Christianity in the Res Gestae but discusses a single statement of Ammianus: his definition of Christianity as absoluta et simplex religio (21.16.18). Neri sees in Ammianus definition a conceited pagan, unwilling to embark on a destructive criticism, but for all that firmly convinced of the inferiority of the Christian culture. What Ammianus did was to criticize the superstitio(n) of Christian leaders (consisting of critical research on simple truths, the scrutari perplexius; 21.16), and praise the religio(n) that was absolute and simple. Ammianus, according to Neri, tried to bridge the gap between Christians and pagans by using his historiographical skills to formulate an ideological message: honourable compromises could be found between Christians and pagans, making it possible for both religions to exist. Of course this would mean that Christianity would only be one of the religions, and thus fall under the umbrella of paganism.
R.L. Rike in his Apex Omnium takes a completely different approach. He concentrates not on Ammianus opinion about Christians, but rather on Ammianus religious ideas in general. He begins by ascertaining that Ammianus tends to correlate religious progress with social refinement (or pedigree) (31.2.11; 31.2.9; 31.2.7; 17.12.21; 31.2.23; 14.4.3-5; 31.2.10; 31.2.21; 31.2.42; 27.4.4; 22.8.34; 31.2.15; 22.8.33; 22.8.36; 19.1.7-11; 17.5.1; 18.4.1; 18.6.22; 19.1.9; 28.5.11; 28.5.14). Whenever Ammianus describes a city (the most powerful symbol of progress and refinement), he uses it as a stepping-stone to talk about religion (15.9.6; 15.10.9; 23.6.24-25; 19.1.6; 22.16.3; 22.15.28; 22.16.7; 22.14.6-8,15,17; 22.16.15; 22.16.9-11). Together with the cities come the refinements of statues and other symbols of religion. The Apex Omnium that Rikes book-title refers to, is Ammianus designation of the Obelisk of Heliopolis (17.4.12). Ammianus saw in the worship of Sol, God of the Obelisk, a certain way to sustain the Roman Empire (17.4.20). The fact that the Egyptians held their empire together for such a long time while serving this god, might have had much to do with Ammianus hope.
In comparison with the brilliance of the Egyptian religion, refinement and cities, Christianity must have appeared rather bleak to Ammianus. The Christian religion had no empire-sustaining history, but Ammianus hoped that Christians would close ranks under the umbrella of the Graeco-Roman cultus deorum, and start defending the Graeco-Roman civilisation.
In his chapter Christian language and anti-Christian polemic, Barnes presents a rather different view of Ammianuss attitude towards Christianity. He sees a conflict between the conscious attempt of Ammianus to take an outsider-position, even deliberately trying to marginalise Christianity, for instance when he twice glossed the word synodus with the phrase ut appellant (as they call it) (also 22.12.8; 27.12; 29.1.1-4; 30.1-2; 15.7.7-10). Ammianus omission of Christian achievements, according to Barnes, can be taken as effective covert insult to Christianity (19.13.2; 22.8.8; 14.7.8; 14.8.11-12). Meanwhile, at a deeper level of the text, Ammianus can be caught unconsciously using Christian modes of thought (25.4.1-3) and expressions (29.3.4; 31.12.9). Barnes points out that the analogy of Julian, whose writings exhibit a similar linguistic phenomenon suggests that Ammianus, too, was an apostate Christian.