Blessed are the pure in heart, for they shall see God. Mat 5:8
Purity of heart is the prerequisite of seeing God. God desires a pure heart. The motives of a heart matter to Him the most, than our actions. With men to attain purity is impossible. We are a people of impure lips and deceitful hearts.
But, God made this possible through our Lord Jesus Christ. He gave himself for us to purify His people. When He died on the cross, the veil was torn and we got access to the throne of grace, by faith in Christ alone.
Through Christ, as we approach HIS throne of grace, take our sinful hearts and repent before Him in humility, He is so faithful to forgive us of all our sins and cleanse us from all our impurities and unrighteousness. HE gives us HIS grace, and enables us to live by HIS rules and live a life pleasing to God.