Faith includes an "assurance of things hoped for" (Hebrews 11:1). This assurance comes only from Heavenly Father. True faith will always be accompanied by this heavenly assurance. No matter how strongly we cling to a false belief, we will never receive a spiritual assurance to accompany it.
Divine assurance comes to us through the power of the Holy Ghost. Being a spirit Himself, the Comforter touches our spirit, bringing the inner peace Jesus Christ promised (see John 14:26-27).