He printed at the same time his treatise Of Faith and Works against Desmarets, and against the error of the inadmissibility of grace, under the title of Explicatio trium illustrissimorum locorum Novi Testamenti, Capitis I. Pauli ad Ephesios posterioris, Capitis II. Jacobi Commatis XIV. & sequentium, Capitis III. Epistolæ I. Johannis, in quibus agitur de fide & operibus. This work shews, that faith is not sufficient for Justification; and that if those who have faith live in sin, they are hated by God.
Via ad pacem ecclesiasticam was printed in 1642: it contains the Consultation of Cassander presented to the Emperors Ferdinand I. and Maximilian II. accompanied with remarks by Grotius. He expected that these works, which were compiled solely with a view to promote union among Christians, would procure him many enemies; and he adopted, on this occasion, what was said in 1557 by an author who laboured in the same design, That for persons to endeavour to make mankind live in peace, was commendable; that they might indeed expect a recompence from the blessed Peace-maker, but they had great reason to apprehend the same fate with those, who, attempting to part two combatants, receive blows from both. "Perhaps, by writing to reconcile such as entertain very opposite sentiments, I shall offend both parties: but if it should so happen, I shall comfort myself with the example of him who said, If I please men I am not the servant of Christ."
Grotius, content with gratifying his pacific desires, expected his reward from posterity; which he clearly intimates in some verses written by him on this subject
Accipe sed placidis, quæ si non optima, certe,
Expressit nobis non mala pacis amor.
Et tibi dic, nostro labor hic si displicet ævo,
A gratâ pretium posteritate feret.
Rivetus, the Clergyman, treated Grotius with as much indignity, as if he had attempted to destroy the foundations or Christianity. Grotius answered him in a tract, entitled: Animadversiones in animadversiones Andreæ Riveti.
This work was followed by two others on the same subject: Votum pro pace ecclesiasticâ, contra examen Andreæ Riveti, and Rivetiani Apologetici Discussio: this last did not appear till after the author's death.
He wrote, in 1638, a small piece, entitled: De Canæ administratione ubi Pastores non sunt, item an semper communicandum per symbola. The design of this pernicious work is to shew, that Laymen, in the absence of Priests, and in cases of necessity, may do their office.
Rigaut had already maintained this error, and been smartly attacked by M. De l'Aubepine, Bishop of Orleans: all the defenders of the hierarchy were scandalized at it, and Father Petau, among the Roman Catholics, and Dodwell, among the English Clergy, have refuted it.
In the tract, An semper communicandum per symbola, the Arminians endeavour to maintain, that we are not obliged to communicate with such as require subscriptions to which we cannot assent without acting against our consciences. Grotius's design was to shew, that the Arminians might dispense with communicating with the Contra-Remonstrants, if these insisted on retractions.
Another theological work of Grotius (of whose publication we cannot fix the time) is entitled: Dissertatio historica ac politica de dogmatis & ritibus & gubernatione Ecclesiæ Christianæ, de dogmatis quæ reipublicæ noxia sunt, aut dicuntur. In this piece he treats of the end of the priesthood, and the duties of the Priests: he places what relates to the distinction and unity of the three Persons, the two Natures, and their properties, among the points of which we may be ignorant without ceasing to be good Christians. It is probable this piece was written before those concerning Antichrist, the author appearing in it less favourably disposed towards the Roman Catholics and the Pope.