Establish Your Heart

Whatever a man establishes his heart upon, that will be precious to him and define his character.  As a Christian, we must establish our heart upon the rock of Christ, as He is the cornerstone of all we believe and live. How we live speaks louder than our words. We may say that Jesus is the most precious thing in our life, but, if we fail to pursue righteousness in ALL we do then we are just talking and fooling ourselves and maybe others. It is in the secret place where our heart exposes us. We may mask our heart in righteousness for most to see and not really have it established in Christ, we may even deceive ourselves, consider what the prophet Jeremiah wrote in chapter 17, verse 9:
“ The heart is deceitful above all things,

      And desperately wicked;

      Who can know it? "
In the next verse the question is answered,  "I, the Lord, search the heart,I test the mind, even to give every man according to his ways, according to the fruit of his doings." We must maintain our fellowship with the Lord to allow Him to show us where our heart is established based upon His standards from the word and not ours. Consider Psalm 139, verses 23-24:
  Search me, O God, and know my heart;

         Try me, and know my anxieties;

 And see if there is any wicked way in me,

         And lead me in the way everlasting.

And again in Psalm 119:
 ⁹ How can a young man cleanse his way?

         By taking heed according to Your word.

 ¹⁰ With my whole heart I have sought You;

         Oh, let me not wander from Your commandments!

 ¹¹ Your word I have hidden in my heart,

         That I might not sin against You.

 ¹² Blessed are You, O LORD!

         Teach me Your statutes.

There is a modern teaching that says the heart has been permanently changed by the sacrifice of Christ as we accept it unto salvation, in other words for those truly saved and regenerated, it is said that it is impossible for that heart to harbor sin any longer, in fact it has been said that it is absolutely blasphemous to say so. I see this as a misunderstanding of the two types of sins Christ came to forgive and die to make payment for us in our place. The first sin is the Adamic sin nature, the nature we were born into being from the bloodline of Adam, this Sin has been permanently forgiven in the Christian believer. The second type of sin is the trespass sins, those we fall into from our old fleshly nature, as we walk out our salvation, these occur as we make poor choices in our daily lives, hopefully, we keep short accounts on these and do not allow these to become a practice in our lives. We cannot practice sinful behavior and be joined to Christ and have fellowship with our Lord. We can have these sins forgiven as we confess them and move on to learn from these temporary failures. Precept by Precept, line upon line, He's changing you and I to reflect His glory.
The unbeliever cannot have these trespasses forgiven, until they have had the Adamic Sin nature changed into a new creation, born afresh. We have constant choices to make as new believers, if we only make right choices with our heart established, then it is possible to go and sin no more. If, however, we fall into sins, being drawn away by the lusts and desires of our fleshly nature(old nature), then there must be a repentance and correction unto righteousness. Consequences may or may not be required to be paid by us, but for the Christian, these sins are permanently forgiven and forgotten by our Lord and Savior, and should be by us. There is a responsibility for the believer to continue in His word and establish his/her heart for righteousness.
1 John 3 tells us the following:

¹⁸ My little children, let us not love in word or in tongue, but in deed and in truth. ¹⁹ And by this we know that we are of the truth, and shall assure our hearts before Him. ²⁰ For if our heart condemns us, God is greater than our heart, and knows all things. ²¹ Beloved, if our heart does not condemn us, we have confidence toward God. ²² And whatever we ask we receive from Him, because we keep His commandments and do those things that are pleasing in His sight. ²³ And this is His commandment: that we should believe on the name of His Son Jesus Christ and love one another, as He gave us commandment.

How is it that John says in the next verse(24) the following? "Now he who keeps His commandments abides in Him, and He in him. And by this we know that He abides in us, by the Spirit whom He has given us." We see that it is imperative that we keep this commandment to believe on the name of Jesus an love one another, these words were not written to those without salvation, but to children, already regenerated.  They were told to keep or maintain their belief in Jesus by what means? In the next chapter, by testing and not believing every spirit, keeping yourself from idols (chapter 5). We must establish our heart on a continual basis or we will damaged by our wrong choices.