When we allow “the Bible to explain the Bible,” we will not come to erroneous conclusions.
Consider Paul's own conversion:
He was on his way to Damascus to persecute Christians when Jesus supernaturally appeared to him... Paul asked Jesus, “What shall I do?” Jesus said, “Arise and go into the city, and you will be told what you must do” (Acts 9:4-6; 22:10). Paul (demonstrating his belief in Jesus) proceeded to Damascus where he fasted for three days and was “praying” (Acts 9:8-11), awaiting further instructions.
... God always uses people to teach people the Gospel. ...God used Ananias, who said to Paul: “And now why are you waiting? Arise and be baptized, and wash away your sins, calling on the name of the Lord” (Acts 22:16). Notice Ananias, God’s specially chosen messenger to Paul, did not tell Paul that his sins were washed away when Paul spoke to Jesus on the road to Damascus (Acts 9:4-6), or when he fasted for three days (9:9), or when he prayed (9:11). Even though Paul had seen Jesus, talked to Jesus, and sincerely fasted and prayed, he had not yet “called upon the Lord.” Acts 22:16 indicates that he “called upon the Lord” and had his sins washed away by the blood of Jesus when he took the final step on his way to becoming a Christian—when he was “baptized into Christ Jesus” (Romans 6:3-4).
Paul’s “calling on the name of the Lord” harmonizes perfectly with Peter's instructions in Acts 2. Peter quoted from the prophecy of Joel and told those in Jerusalem on Pentecost that “whoever calls on the name of the Lord shall be saved” (Acts 2:21; Joel 2:32). The people in Acts 2 did not understand Peter’s quotation of Joel to mean that a sinner must pray to God for salvation. ... Furthermore, when Peter responded to their question and told them what to do to be saved, he did not say, “I’ve already told you what to do. You can be saved by petitioning God for salvation through prayer. Just call on His name.” On the contrary, Peter had to explain to them what it meant to “call on the name of the Lord.” Instead of repeating this statement when the crowd sought further guidance from the apostles, Peter commanded them, saying, “Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins” (Acts 2:38).
In Romans 10:13, Paul (like Peter in Acts 2) quoted from Joel 2:32: “[W]hoever calls on the name of the Lord shall be saved.” When we allow “the Bible to explain the Bible,” we will not come to the erroneous conclusion that Paul is commanding the unbelieving Jews in Romans 10 to merely “cry out to the Lord” (cf. Matthew 7:21) or to “pray the sinner’s prayer.” Rather, with Paul’s own conversion in mind (his “calling on the name of the Lord”—Acts 22:16), as well as those on Pentecost (Acts 2), we realize that in Romans 10 Paul is pleading with (especially) the Jews, who “have not all obeyed the gospel” (Romans 10:16) to “call on the name of the Lord”—that is, to “obey the gospel.” And to “obey the Gospel” is to hear and believe the Gospel (Romans 10:17), to repent of sins (Romans 6:2,6; Acts 2:38), to make the good confession that Jesus Christ is the Son of God (Romans 10:9-10), and to be immersed in water for the remission of sins (Romans 6:3-4; Acts 2:38; 22:16)." (AP excerpt)