The Difference That Greek Prepositions Make (More from Harris)

Originally, then, it was the case that showed the meaning of the preposition, but ultimately the preposition was regarded as giving a particular meaning to the case. To express the point another way, at the outset cases “governed” prepositions, but in the end prepositions were thought to “govern” cases in the sense of determining the case of a noun or pronoun that would produce a specific meaning. Since a plain case is often capable of various senses, an added preposition or prepositional phrase can clarify and reinforce the intended meaning or actually remove ambiguity. For example, a phrase such as ἡ ἀγάπη τοῦ Χριστοῦ (2Co 5:14) could mean “the love shown by Christ” (subjective genitive) or “love for Christ” (objective genitive), but ἡ ἀγάπη ἡ ὑπὸ τοῦ Χριστοῦ would express the former meaning unequivocally.

(Murray J. Harris, Prepositions and Theology in the Greek Testament)