“Beware, brethren, lest there be in any of you an evil heart of unbelief in departing from the living God; but exhort [encourage] one another daily, while it is called ‘Today,’ lest any of you be hardened through the deceitfulness of sin.” Hebrews 3:12-13.
The dictionary defines evil as, morally wrong; immoral; wicked. It could be something harmful or injurious; the synonyms though may be the best descriptions.
Depending on how it is used evil can be; sinful, iniquitous, depraved, base, vile, nefarious, pernicious, destructive, wickedness, unrighteousness, or corruption, to name a few.
“Now it happened, as He was dining in Levi’s house, that many tax collectors and sinners also sat together with Jesus and His disciples; for there were many, and they followed Him. And when the scribes and Pharisees saw Him eating with the tax collectors and sinners, they said to His disciples, ‘How is it that He eats and drinks with tax collectors and sinners?’ When Jesus heard it, He said to them, ‘Those who are well have no need of a physician, but those who are sick. I did not come to call the righteous, but sinners, to repentance.’” Mark 2:15-17.
“For we did not follow cunningly devised fables when we made known to you the power and coming of our Lord Jesus Christ, but were eyewitnesses of His majesty.” 2 Peter 1:16.