"'Whoever will call on the name of the Lord will be saved'" (Ro 10:13). "How then will they call on Him in whom they have not believed? How will they believe in Him whom they have not heard?" (:14). Fortunately "faith comes from hearing, and hearing by the word of Christ" (:17). The Greek term for "word" is "rhema" which means uttered by a living voice. The "word of God is quick" (Heb 4:12) which means it is alive. When God speaks, it is present tense having "been granted for Christ's sake" (Php 1:29) to "believe in Him" (:29). "Having also believed, you were sealed in Him with the Holy Spirit of promise" (Eph 1:13).
Without knowing the truth you don't have faith to believe. It comes by "listening to the message of truth, the gospel of your salvation" (Eph 1:13). It is "hope laid up for you in heaven, of which you previously heard in the word of truth, the gospel" (Col 1:5). It has worked in you "since the day you heard of it and understood the grace of God in truth" (:6). It is "the hope of the gospel that you have heard, which was proclaimed in all creation" (:23). "You have heard Him and have been taught in Him, just as truth is in Jesus" (Eph 4:21).