I do not know of any more important truth to bring before an unconverted person than the answer to the question, "What must I do to be saved?" That is the beginning of everything with regard to the divine life. A person must know they are saved before there is any peace, or joy, or comfort.
The answer to the question is, "Believe in the Lord Jesus, and you will be saved," and the question that comes right after that from almost everyone is, "What is it to believe? I believe that Jesus Christ is the Son of God; I believe that He came into the world to save sinners."
Well, so do the devils. The devils not only believe, but they tremble! If our faith is in churches, and dogmas, and creeds, and people, in this thing and that, we will plunge into trouble and difficulties before we get through our pilgrim's journey. But for the person who has faith in God, the light will shine brighter and brighter, until they come at last into the glory of the perfect day.