Is worshipping Goddesses as a Catholic sinful even if I am very religious and love Jesus Christ?
I should say so! Such behavior is mortally sinful. The first Commandment (I am the Lord your God; you shall have no strange gods before me.) is not only first chronologically, but also first in importance. A goddess is a female god. We are bound to worship the one, true God and Him alone!
Fr. Vincent Serpa, O.P.