What makes an “urgent request” powerful? James says that righteousness makes our prayers effective, i.e. “very powerful.” And what does James define as “righteousness?” He says that righteousness is the direct result of healing. How does James say we are healed? He says that healing comes from confession of sins.
“Therefore, confess your sins to one another and pray for one another, so that you may be healed. The urgent request of a righteous person is very powerful in its effect.”
Simply put, don’t go before God the Father in prayer without first confessing your sins. With confession comes His healing, and with His healing comes righteousness, and with righteousness comes power.