19.34 – That was Jesus, son of Mary – a statement of the truth about which they are in doubt
For the quranic name ‘Īsā, see the explanation at 2.87. This verse can be understood to call ‘Īsā himself a “statement of the truth” ( qawla ’ l-ḥaqq ), thereby matching what the Quran says about ‘Īsā in 3.45 and 4.171.
In a more straightforward sense, the verse represents well the quranic presentation of ‘Īsā: a tone of finality, a claim to truth about the matter (see also 3.60–62; 4.174), and a suggestion that the People of the Book are in dispute (see also v. 37).
As for the “factions” (v. 37) doubting or differing about ‘Īsā, during the seventh century Byzantine, Nestorian, and Monophysite Christians all believed in the death and deity of Jesus. They differed about how to express Jesus’ humanity. See the comments on the theme of disagreements at 98.4.