We hear that often. But what does that actually mean? Is it wrong? Is it right? Is it horrible advice, or is good advice?
Potentially, it could be all of the above.
Allow me to try to process this a bit here...
Some Christians go too far in their preaching and proclaiming that the heart is evil and so easily deceived (citing Jeremiah 17:9 as their proof). But then there are other Christians who go too far in their belief that the heart is good.
But, I'm beginning to think that neither of these answers are correct on their own, nor fully, but like many great truths in scripture the wiring of the heart is a paradox--meaning that where differences occur that would seem to contradict each other, in fact do not. Much of the human heart is mysterious I find, which is maybe why David said it would take acts of unriddling paired with the act of inclining oneself to the wisdom of God, in order to unearth its workings.
Let's actually take a look at Jeremiah 17:9; it reads "The heart is deceitful above all things, and desperately sick; who can understand it?"
Anytime we study a singular verse it's imperative that we look at it's context within the surrounding verses, the chapter, the book, and the whole of scripture. If we practice this Bible study skill, then to say that a human heart is at all times evil and can never be trusted, is actually faulty.
The whole book of Jeremiah, like many Old Testament books, is about a time, a season, in which God's people had turned away from the covenant between the two, and sin was rampant. More specifically Jeremiah takes place during the last years of Judah existing as a nation, so there's tons of upheaval happening. Chapter 17 of Jeremiah in its whole is addressing Judah's sin specifically, and within this chapter, verses 5 through 10 are contrasting the man who trusts in God and the man who trusts in his/her own ways; verse 9 is the descriptor of the latter (a man who trusts in his own way). The question here is never the heart itself good or evil, but in who is this person giving the authority of his heart to? Is it himself, or is it the Lord? Or as I said in the previous post: "Who do you say is Jesus?" It's circling back to the question of who has the inner authority and reign. (Really important to read that last two posts if you're following my train of thought, so if you missed it, go back here.)
In the bigger picture of scripture, those living during the Old Testament times were under the Old Covenant, which is an extremely important detail to keep in mind here, because with the death and resurrection of Christ we have the forming of the New Covenant; the covenant that you and I as Christians living now are covered under. Later on in Jeremiah and in other Old Testament books, God's people were given the promise that they would no longer carry in them hearts of stone but hearts of flesh, hearts that would house his presence (i.e. the Holy Spirit) (Ezekiel 11:9 & 36:26, & Jeremiah 24:7).
It's in surrendering to Christ--giving and trusting him as our inner authority--that we're regenerated; we receive the new heart (John 3:3) that was promised. We live in light of the knowledge that our hearts are finding their source in Christ, and because of that they're constantly being refined into the image of His heart now. *The description of the heart found in Jeremiah 17 is not that of believers, but of those who've yet to give their lives over to Christ.
That question leave much to be desired in its sheer formation. It's not a horrible question, but it's not a great one either. The question should not be should I listen to my heart, but what or who is my heart listening to?
Our hearts are our core, but they have a source that informs them, leads them, and affects everything we do, say, and think.
*After looking up this verse in a handful of different commentaries, including the ESV footnotes, this is what many of the theologians agreed upon.