Salvation provides the breastplate of righteousness. God designed the breastplate to protect our heart. We put it on by seeking a personal relationship with Him and living according to His direction. Through this relationship our hearts get purified and this reflects in our actions.
Remember, the breastplate of righteousness is only one piece of the protective armour we are directed to put on in Ephesians 6:10-19 KJV
E. A. Fussell 