These appear to be quotes from your sources, that should appear in quotation marks:

The druids worshipped outdoors and did not have chapels or churches. Druidic rituals were held in oak groves, and these groves were very sacred to them.

To listen to the voice of the divine, one should stand under the oak tree. The druids gathered in the oak groves to listen to the voice of the divine and to perform their rituals.

Otherwise, it looks great!