The Holy Bible says,

The heart is evil from childhood...(Genesis 8:21).

The heart of men are full of evil and there is madness in their hearts while they live. (Eccl. 9:3).

For out of the heart come evil thoughts, murder, adultery, sexual immorality, theft, false testimony, slander.(Matthew 15:19; Mark 7:21,22).

Each of us will follow the stubbornness of his evil heart. (Jeremiah 18:12).

The heart is deceitful above all things and beyond cure, who can understand it? (Jeremiah 17:9).

Is your heart deceiving you?

Yes, The heart is treacherous. Now it's important why we need to be directed by Jehovah God and his Son Jesus Christ. We have been sidetracked for so long.
...for not the way man sees God sees, because mere man sees what appears to the eyes, but as for Jehovah he sees what the heart is 1 Sam.16:7