We are ambassadors for Christ, God’s representatives on earth.  (2 Corinthians 5:20)  Like earthly ambassadors of states, we are to represent our country and Leader in the very best light possible.

“Keep your behavior excellent among the Gentiles, so that in the thing in which they slander you as evildoers, they may because of your good deeds, as they observe them, glorify God in the day of visitation.”                               1 Peter 2:12

Although this our assignment and goal, we often fail to represent our Master’s beauty clearly.  We can distort His image.   “Like a trampled spring and a polluted well
is a righteous man who gives way before the wicked.”        Proverbs 25:26

If our hearts are misdirected to the visible world and the satisfaction our own selfish ends, we will be poor ambassadors of our King.  It is a heart issue.

“The good man out of the good treasure of his heart brings forth what is good; and the evil man out of the evil treasure brings forth what is evil;  for his mouth speaks from that which fills his heart.”      Luke 6:45       For this reason, we are to “watch over your heart with all diligence, for from it flow the springs of life.”      Proverbs 4:23

How are we to do this, to watch over our hearts?  One strategy is to guard what goes into our hearts.  We should keep a “doorman” at the gateway to our minds and hearts, only allowing entrance to edifying thought-guests, those who have His invitation to enter, and out-going passage to word-guests and actions which honor our King.
“The eye is the lamp of the body; so then if your eye is clear, your whole body will be full of light.  But if your eye is bad, your whole body will be full of darkness.  If then the light that is in you is darkness, how great is the darkness!”        Matthew 6:22-23          

Guarding of the door of our hearts goes far to cleanse our innermost being, that we will not pollute the well or trample the spring of God’s reputation on earth.