The Apostle Paul writes in Romans 10:13 those blessed and often repeated words: "For whosoever shall call upon the name of the Lord shall be saved." But he does not stop in verse 13 but goes on in verse 14 to say something vitally important. "How then shall they call on him in whom they have not believed? And how shall they hear without a preacher? And how shall they preach except they be sent?" What the apostle is saying is that all true, saving faith is based upon certain revealed knowledge! You don't call on one you do not believe in, you don't believe in one that you've never heard of and you don't hear of God's Christ apart from God sending a messenger. There are some five areas in which you must have knowledge in order to believe and call upon the Christ of the scriptures.
First, you must know God in his true character! There aren't many people in our day who know who God is. They worship a god who is merely the product of the family religious tradition or the idolatrous figment of their imagination. God's true character is revealed in the scriptures…all of them! God is absolutely sovereign over all things. (Isaiah 46:9-11; Daniel 4:35-37; Romans 9:11-24) God is inflexibly just. (Ezekiel 18:20; Galatians 3:10) God is infinitely gracious. (Micah 7:18-20); Romans 3:24-26)
You must know yourself in your true character! Man is spiritually dead. (Ephesians 2:1-3) His heart is depraved and desperately wicked. (Matthew 15:19; Jeremiah 17:9) He is justly condemned by the law of God. He is self-deceived and Satan-deceived and has neither the desire or the ability to change his condition. You cannot know your true character by what you feel or by what others say; only by what God says in His Word. (John 5:40, 6:44)
You must know the Lord Jesus Christ in His true character! Jesus Christ is God come to earth in human flesh. He is both God and man in one unique person. Being man, He is able to suffer the penalty of sin. Being God, He is able to satisfy the claims of Divine justice (I Timothy 3:16; Hebrews 10:12-14)
You must know what happened at the cross! It is not simply a good man, prophet or teacher dying a martyr's death. Nor is it even Christ dying to make salvation possible. It is Christ dying for the sins of His people and thereby saving them. By His one great sacrifice for sin, Christ satisfied the justice of God for those He represented and put away the sins of His elect. As Isaiah says in chapter 53 verse 10 and 11 "Yet it pleased the Lord to bruise him; he hath put (him) to grief; when thou shalt make his soul an offering for sin, he shall see (his) seed, he shall prolong (his) days, and the pleasure of the Lord shall prosper in his hand. He shall see of the travail of his soul, (and) shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities."
You must be reconciled to God in your heart! To be reconciled to God is to justify God (Psalm 51:4), to willingly bow to Christ as Lord (Luke 14:25-33), and to trust Christ alone for all your salvation and in all things (Romans 10:9-13). We must not only with your head believe these things to be true…you must in your heart believe them to be right!
Men are not called upon in scripture to "just believe." Knowledge is required and provided in God's word. If we are to know Christ so as to believe on Him, this knowledge must come through the preaching of the gospel. What a responsibility we have to take Bible in hand and seek out some messenger of God who is preaching the Christ of the scriptures and His gospel of grace.