Satan has deceived man to keep him from the gospel. The gospel is clearly offered, yet many are blinded from it (2 Cor 4:4). Because Satan has presented a deception that is enticing to satisfy our rebellious spirit. His first attempt was as a Serpent to deceive Eve and entice her to eat of the fruit of the tree of the knowledge of good and evil, violating a law of God (Genesis 3). In this account he laid out reincarnation, narcissism, and Gnostic knowledge. And gave her the idea that she would become as god. And this to develop and influence false religion and false doctrine to keep mankind from salvation (Rom 1). This has led to an apostasy of the faith even in the church (2 Thes 2:3, 1 Tim 4:1).
2 Cor 4 esp v4