Purity is an absolute measure.  Something is either pure or impure; it cannot be 99% pure … because it is then impure.  To be 'pure in heart’ is to be 100% free from sin, and totally pleasing to God. “… without holiness no one will see the Lord” (Hebrews 12:14).  This is a tough standard, especially when we consider that holiness is not measured over an hour or a day – but over a lifetime.

Jesus places 'purity of heart' as the condition for seeing God.  This seems an impossible objective because nobody except Jesus has ever lived a totally pure life (Hebrews 4:15).  And we cannot make ourselves pure if we have previously been impure, because just one impurity disqualifies us from the joy of God's presence.

And yet Jesus promises joy in God's presence for those whose hearts are pure.  How can this be?  Although it is impossible for us to mask previous failure by good deeds, the death of Jesus paid for the offence of our impurity and as we repent of it, He takes it away (Psalm 103:12, Micah 7:19).  So, our purity is not the result of our perfect record, but of His removal of our imperfections ... as His grace meets our repentance. Then we find great joy in experiencing the presence of God.

Our happiness is directly related to our purity, because any shadow of sin removes the joy of our salvation (Psalm 51:12).  Every believer is urged to continue in pure living by discerning what is best (Philippians 1:10), refusing to complain and argue (Philippians 2:14-15) and by obeying the truth (1 Peter 1:22).  Every time we fail, we need to repent, confess our sin and ask the Lord to take it away (1 John 1:9).  Living in the grace of Christ is the only route to real happiness and to the assurance of His presence with us each day until we see Him face to face.