When confronted with the numerous human rights violations promoted by the old testament (genocide, slavery, death penalty for gays, captive virgin women to be used as sex slaves, virgins to be married to their rapists, kill everyone who worships other gods, etc), a lot of modern Christians say "oh, that's the old testament, the old covenant, we don't follow that, we follow the gospels" or something like that. There are even Christians that say the god from the OT was a different god from the NT, that the god from the OT was a god of punishment and the god of NT as a god of love. There are a number of different reasonings they give to cope with the terrible parts of the OT.

Of course one would argue that the only reason that Christians today kind of dismiss parts of the OT is because we as a global community developed new moral/ethical values after the Enlightenment that pretty much led to the creation of the concept of human rights for every individual, and without the values of the Enlightenment the Christian world would not have a problem with the "bad parts" of the OT, given the fact that Christians unapologetically commited a number of human rights violations very similar to the ones in the OT.

My question is, how was the Old Testament historically viewed by the Christians, from the early Christians in the 1st century to, let's say, the 19-20th Christians? Did influential Christians writers from the past centuries said anything about the OT being not to be followed, like modern Christians do?