Efficacy n. : Power to produce effects; operation or energy of an agent or force; production of the effect intended; as, the efficacy of medicine in counteracting disease; the efficacy of prayer.

Example:
What are some ways to strengthen political Efficacy?

Taxonomy
efficacy, Saint Louis, MO, Concordia Publishing, Publishing House, free encyclopedia, Luminous efficacy, power, watts, Vaccine efficacy, Graebner, Augustus, Engelder, Theodore, capacity, power of the Holy Spirit, Pharmacology, visible power, common-mode rejection ratio.

Defination from the web:
efficacy ... In Lutheranism efficacy is used to describe the characteristics of Scripture. The efficacy of Scripture means that it is united with the power of the Holy Spirit and with it, not only demands, but also creates the ...