He was unceasing in his prayers and appeals for "mutual toleration on the subject of predestination." Perhaps the bitterness, almost amounting to frenzy, with which abstruse points of casuistry were then debated, and which converted differences of opinion upon metaphysical divinity into deadly hatred and thirst for blood, is already obsolete or on the road to become so.

If so, then was Barneveld in advance of his age, and it would have been better for the peace of the world and the progress of Christianity if more of his contemporaries had placed themselves on his level.
He was no theologian, but he believed himself to be a Christian, and he certainly was a thoughtful and a humble one.

He had not the arrogance to pierce behind the veil and assume to read the inscrutable thoughts of the Omnipotent.

It was a cruel fate that his humility upon subjects which he believed to be beyond the scope of human reason should have been tortured by his enemies into a crime, and that because he hoped for religious toleration he should be accused of treason to the Commonwealth.
"Believe and cause others to believe," he said, "that I am and with the grace of God hope to continue an upright patriot as I have proved myself to be in these last forty-two years spent in the public service.

In the matter of differential religious points I remain of the opinions which I have held for more than fifty years, and in which I hope to live and die, to wit, that a good Christian man ought to believe that he is predestined to eternal salvation through God's grace, giving for reasons that he through God's grace has a firm belief that his salvation is founded purely on God's grace and the expiation of our sins through our Saviour Jesus Christ, and that if he should fall into any sins his firm trust is that God will not let him perish in them, but mercifully turn him to repentance, so that he may continue in the same belief to the last." These expressions were contained in a letter to Caron with the intention doubtless that they should be communicated to the King of Great Britain, and it is a curious illustration of the spirit of the age, this picture of the leading statesman of a great republic unfolding his religious convictions for private inspection by the monarch of an allied nation.
More than anything else it exemplifies the close commixture of theology, politics, and diplomacy in that age, and especially in those two countries.
Formerly, as we have seen, the King considered a too curious fathoming of divine mysteries as highly reprehensible, particularly for the common people.