Secular is the opposite of Religious. Religious is related to Believe. Believe is a type of Expect. 
Agricultural is related to Grow. Grow is related to Culture. Culture is related to Music. 
Secular <--Antonym--> Religious <--RelatedTo--> Believe --IsA--> Expect 
Agricultural <--RelatedTo--> Grow <--RelatedTo--> Culture <--RelatedTo--> Music 