- On the one hand, it was written by a man who actively participated in enslaving and transporting enslaved people from Africa to the Americas. (I knew this, but until I looked him up today I didn't know that he himself had been enslaved, although only for months, not a lifetime.)
- On the other hand, its message is one of forgiveness and redemption of sins.
IMHO the way to reconcile is to believe that humans are prone to error (my Calvinist forebears would say "original sin"), but change and redemption can happen, whether by God's grace or otherwise, and we must accept all humans as human.