As Southern men with means, they both owned slaves. Boyce called himself ultra pro-slavery, whereas Broadus seemed to be more of a reluctant slaveholder. Broadus was, in this respect, much like that great Southern General Robert E. Lee, who though he had slaves longed for the day when he did not (Bound to Be Friends: Slavery and Friendship in the Lives and Thoughts of James P. Boyce and John A. Broadus). While loyal to the South and ultimately supportive of the War, they did not favor secession. However, once the South seceeded, they both actively supported the Confederate troops as chaplains.
Boyce thought slavery was being removed by God as a punishment on America for neglecting the slaves marital and religious rights. He said that God had allowed slavery as long as he did in America to show us how great we might have been had we treated the slaves properly. He wrote to his brother-in-law, H.A. Tupper:
I believe I see in all this the end of slavery. I believe we are cutting its throat, curtailing its domain. And I have been, and am, an ultra pro-slavery man. Yet I bow to what God will do. I feel that our sins as to this institution have cursed us, - that the Negroes have not been cared for in their marital and religious relations as they should be; and I fear God is going to sweep it away, after having left it thus long to show us how great we might be, were we to act as we ought in this matter. (John A. Broadus, “Memoirs of James Pettigru Boyce,” in Selected Works of John A. Broadus  4:185).Broadus, as already mentioned, was a reluctant slaveholder, and not eager to defend the practice; nevertheless, as was customary in his day, he felt the negro race to be a "lower grade of humanity." He stated:
We must not forget that the Negroes differ widely among themselves, having come from different races in Africa, and having had very different relations to the white people while held in slavery, many of them are greatly superior to others in character, but the great mass of them belong to a very low grade of humanity. We have to deal with them as best we can, while a large number of other white people stand off at a distance and scold us. Not a few of our fellow-citizens at the north feel and act very nobly about the matter; but the number is sadly great who do nothing and seem to care nothing but to find fault (Quoted from: “A Sermon on Lynch, Law, and Raping: Preached by Rev. E.K. Love, D.D. at 1st African Baptist Church, Savannah, Ga., of which he is pastor, November 5th, 1893.” [Augusta: Georgia Baptist Print, 1894], 11).So, here again,we find Evangelical Christians defending slavery, even as it was practiced in the antebellum South. Granted, they would like to have eliminated some of the abuses, and Broadus especially felt that it was wrong to prohibit slaves to marry and to attend religious services; but the fact still remains that they did not see anything unbiblical about the essence of slavery. These men believed the Bible was the Word of God and on that basis they defended the practice of slavery.