Jesus has put purity in the right perspective by attaching the heart’s purity in it. Till then, outward purity is what everyone thought about and practiced; whereas, the heart is the seat from where all these issues originate. Mark 7:20 [NLT]  And then He added, "It is what comes from inside that defiles you.”

During the time of Jesus, Jews had strict laws concerning purity in every walk of life. They with much religious fervency went about with the strict adherence of these external purification rights and condemned others who do not follow these practices. One such incident had caused Jesus to clearly explain what the real meaning of purity. Purity has to first start with our heart and then it should control our outside. God works from the inside to the outside; not the reverse. For men the reverse mechanism seems more easy and adaptable. But listen to what Jesus says: Mark 7:15 [NLT]  “It's not what goes into your body that defiles you; you are defiled by what comes from your heart."

Pure in heart:
A pure heart is where true religion has its foundations. We, by nature defiled from inside out; need real cleansing before we could ever understand and differentiate purity from impurity. In the darkened state of our soul we do not understand anything in its clear perspective. Only when our heart becomes pure, we can see all things in its true perspective. That is why in His Beatitudes; Jesus speaks: God blesses those whose hearts are pure, for they will see God. Matt. 5:8 [NLT]  

Effects of heart’s purity:
Let us look at the ways in which this heart purity affects our daily life. As we read ‘Everything is pure to those whose hearts are pure. But nothing is pure to those who are corrupt and unbelieving, because their minds and consciences are corrupted.'

Paul here talks about the attitude of a person, which is directly proportional to the state of the heart of a person. It affects the way a person views his own life and all that surrounds him. If a person is confused and negative, everything he sees around him, he sees with these qualities. On the contrary, if the person is pure in his heart, he will view the same situation positively and will find things to glorify God even amid a difficult situation. So it is this function of the heart that will make a difference in a given situation. This is the clear message we see when the 12 spies went to Canaan to spy the land (Numbers 13:25-33). Except two, all the rest said negative things and confirmed in their own way how they cannot possess the land. Whereas the other two who had faith in God said the contrary. They viewed the situation from God's point of view. They ultimately achieved according to their perception; the others received according to their perception. 
This brings us to the important aspect that 'What you perceive, you receive.' Joshua and Caleb perceived they can possess the land and they possessed it. Whereas others perceived they cannot and they perished in the wilderness. 
 

To Ponder:
How is your perception? Is it according to God's viewpoint or is it tainted

with human wisdom and negativity? If so, will you today ask

God to really cleanse your inside so that you can

see clearly?