What does the Bible say about being deceived?

In Jeremiah 17:9, we learn that 'The heart is deceitful above all things, and desperately wicked: who can know it?' This means that human hearts have an inherent tendency to deceive themselves, which is a key characteristic of fallen humanity. The Apostle Paul echoes this in Titus 3:3, where he describes our past state as being foolish, disobedient, and deceived—showcasing the severity of our condition without divine intervention. True understanding of this nature is crucial for recognizing our need for salvation and liberation from such self-deception.