The Beginning of Sin Is the Existence of Unbelief

Eve was tempted by a snake, and made her doubt/do not believe.
And finally fell into rebellion.

Saul always stepped over authority (Samuel & God) because of his lack of trust.
Which ultimately made him rebel and get involved in witchcraft.

Disbelief = rebellion = witchcraft

The kingdom of God is based on faith. (Believe.)

The beginning of sin is unbelief (John 16: 9).

Follow you heart.
Trust your thoughts.
Believe in yourself.

These things actually directly goes against the word of God.

All of these quotes directly oppose the Truth of God's Word.