James 5:16 …The effective prayer of a righteous man can accomplish much.
This passage is taken from a section in James about the example of Elijah in the Old Testament, and the passage takes us right into the New Testament.
Consider a person with a right standing before God because of faith in Christ. This person experiences daily cleansing of his sins through confession. This person because of their standing with God accomplishes much through their prayer. Notice that the verse does not indicate there will always be an answer, but in the believer much is accomplished towards conforming this person to the image of Christ.
Consider Romans 8:28 And we know that all things work together for good to those who love God, to those who are the called according to His purpose. 29 For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren.
These verse are just after the verses in prayer 27 Now He who searches the hearts knows what the mind of the Spirit is, because He makes intercession for the saints according to God.