Titus 1:15 To the pure all things are pure; but to those who are defiled and unbelieving nothing is pure but both their mind and their conscience are defiled.

For those who have been made pure, all thoughts have the Light of purity when controlled by Holy Spirit. Titus 1:15 To the pure, all things are pure; but to those who are defiled and unbelieving, nothing is pure, but both their mind and their conscience are defiled.