Deceitful and incurable

“The heart is deceitful above all things and beyond cure. Who can understand it?” Jeremiah 17:9
When we talk about our heart, in regards to desires and feelings, we know that we aren’t talking about an organ in our body. But if you ask people what they are talking about, they can’t really explain it.
Our heart is the deepest part of us. We have the body – the vehicle that carries us around. We have the soul – our willpower, personality, emotions. Then we have our heart, our spirit. The fact that we have a spirit it what makes mankind unique and sets us apart from animals (which have souls, but not spirits). The Bible tells us that only the Word of God can separate between the soul and spirit (Heb. 4:12).
In the light of this, we read what Jeremiah writes here: that the heart is deceitful above all things and beyond cure. That is, the heart of an unregenerated person. Think about it: nearly everyone thinks they are a good person, deep down. They may have different definitions of ‘good’, but generally it comes down to ‘I do more good things than bad things.’ But if they would actually take on objective view of their life, they would realise that their motivations are generally selfish, not caring about others. They are being deceived that they are a good person even by their own standards. It is impossible for us to know our own hearts (see Ps. 139:24 – David asks God if there is any offense in him, indicating that he himself does not know).
Jeremiah tells us here that such a deceitful heart cannot be cured. It cannot be cured by psychology, because psychology only reaches the psyche, the soul. It does not reach to the spirit. Only the Word of God reaches to the spirit, and when it does, it shows us that we need a new spirit, given by the Spirit of God. Our hearts cannot be cured – they must be replaced.