Complex sentence: By the time of the mystery religions, Ea was referred to as Oannes (or sometimes considered as Oannes' father), which in greek is written Ioannes (i.e. John); according to the myths, Oannes spent the days teaching mankind wisdom.
Split into simpler sentences: By the time of the mystery religions, Ea was referred to as Oannes (or sometimes considered as Oannes' father), which resembles the Greek word "Ioannes" (i.e. John). According to the myths, Oannes spent the days teaching mankind wisdom.