On Herder.
In short Herder added two ideas to religious philosophy.
1) He reimagined Spinoza’s godhead from a noun to a verb.
2) And he insisted that even the holy scriptures should be read as literature.
Neither of these is philosophical apostasy.
And if Spinoza can be tolerated by some religious authorities, surely there are many more that would tolerate Herder.
PS I’m not making any recommendations. My only focus is if one can read future cultural outcomes into the founding philosopher’s thinking. Of course there were historical conclusions from the work of Herder and Marx. Herder definitely would not be pleased by how it played out. Marx even more so.