After condemning the idolators for their love of Shirk and their hatred of Tawhid, Allah teaches how to call upon Him.
Say: O Allah, Creator of the heavens and the earth, Knower of the unseen and the seen.
This means to call upon Allah alone without any partner, the One who created everything from nothing.
You judge between Your servants concerning that over which they differ.
No ransom will be accepted on the Day of Resurrection. One must turn sincerely to Allah now.