They were anti-Christian but in a different way. Stalin, Kaganovitch and their associates simply killed Christians and blew up churches. The Nazis were molding Christianity into something very un-Christian and gradually replacing that with a teutonic paganism. Unless you were a resisting Christian such as Boenhoeffer, you survived in Nazi Germany. In the Soviet Union, you stood little chance of staying alive.
I would say they were trying to "Aryanize" Christianity. But this is irrelevant because Christianity was "Aryanized" during the early Christian period as the European pagans converted to Christianity. For instance, the birth of Christ was set as December 25, which was a traditional European pagan Holiday.
Traditional Christianity as we know it is in reality a fusion of some pagan European traditions with the traditions of early Christianity. During the process of conversion Christianity itself was transformed.
Thus, in fact, the Christianity that we know is very different from that of the early Christians. Protestantism was in some regards an attempt to make Christianty more like what it was in the early period. While Catholicism and Orthodox Christianity continued to retain that fusion of traditions.
So what I say to you is that whether this Nazi policy was anti-Christian or not depends on what "Christianity" we are talking about. It depends on what we mean by "Christianity" because not all forms of Christianity are the same.