The Essence of Islam – Volume II — Page 291
Salvation 291 to say, to believe in the Messenger of God, is that faith might be established in the Word of God also, for it is necessary for a person who confesses that he desires to become an obedient servant of God that he should believe in God's commandments; and belief in God's commandments is not possible without belief in him through whom the commandments have been conveyed. . This is the true meaning of the credo. [Nur-ul-Qur'ān No. 2, Rūḥānī Khazā'in, vol. 9, pp. 418-420]