Faith is not an issue of the mind, it is an issue of the heart(Psalm 95, Hebrews 3). Scripture warns believers not to harden their hearts, to avoid relying on past spiritual victories, and to faithfully proclaim the gospel in love, as defined by God rather than by culture.
Freedom
Jesus teaches that true freedom is not the ability to do whatever we want, but being set free from the bondage of sin through knowing and following Him, who is the Truth.