Untrustworthy. That is my assessment of my own heart. I have made poor decisions in the past based upon my emotions. I have trusted my own thoughts and plans and found them to be in error. I have convinced myself in the past that wrong is right and right is wrong. I know it to be true that the "heart is deceitful", as Jeremiah says.
Being Decieved is easy. But it is the ultimate betrayal when it is your own heart that betrays you. James tells us that this has roots in a shallow relationship with the Lord. "Do not merely listen to the word, and so deceive yourselves. Do what it says." (James 1:22) Amazingly, it is possible for us to be in church hearing the word, read the scriptures often and yet have a predetermined plan that we will only obey those commands that "make sense" to us. This, of course, means that we are our own Lord and Jesus... well Jesus isn't. As scary as that may be, it gets worse.
We spiral into a deception that is self induced and get farther and farther from the will of God. This is further exasserbated by the religious veil that is cast over our lives. We can lie and decieve, cheat and connive, and lust and covet- all the while we are singing "Praises to Jesus". What we are sometimes to dull to percieve and what others cannot tell at all is that our praises and prayers are rejected from heaven. God rejects those attempts are relationship with him. Isaiah's generation had their hypocritical religious actions rejected by God. He said in Chapter 1
When you spread out your hands,
I will hide my eyes from you;
even though you make many prayers,
I will not listen
It seems like the people going through these actions needed Isaiah to tell them they were wasting their time because they had so decieved themselves.
A sobering thought.