In the following sentence, four words printed in bold type are given. One of these words printed in bold may either be wrongly spelt or inappropriate in the context of the sentence. Find out the word that is inappropriate or wrongly spelt, if any. If the words printed in bold are correctly spelt and appropriate in the context of the sentence then mark 'No error’ as your answer.

Its content is mostly spiritual and esotoric, referencing the Sufi concept of achieving union with God and his wisdom.