When Jesus was crucified, very few people who witnessed his crucifixion believed that he was the Son of God, the King of the Jews.  But as they saw him lifted up, some realized that he was, in fact, the King of the Jews.  Like Jesus said in Jn 8:28, “When ye have lifted up the Son of man, then shall ye know that I am he.”  When they saw him lifted up then they knew.  Notice who knew he was the Son of God.

The people – Lk 23:35 – initially, the people derided him saying, “He saved others; let him save himself, if he be Christ, the chosen of God.”  But after they saw him lifted up, many “beholding the things which were done, smote their breasts, and returned,” [Lk 23:48]. See also Lk 18:13.

The soldiers – Lk 23:36-37 – the soldiers initially mocked Jesus saying, “If thou be the king of the Jews, save thyself.”  But after they saw him lifted up, many of them knew who he was.  The centurion said, “Certainly this was a righteous man,” [Lk 23:47].  Then he and they that were with him said, “Truly this was the Son of God,” [Matt 27:54].

The malefactors – Mk 15:32 – initially they reviled him.  One of the thieves even railed on him, saying, “If thou be the Christ, save thyself and us,” [Lk 23:39].  Then the other thief had a change of heart.  He knew who Jesus was.  And in Lk 23:40-43 you see this malefactor saying, “Lord, remember me when thou comest into thy kingdom,” [Lk 23:42].  That’s great faith considering he was watching Jesus die.

The rulers – Lk 23:35 – they reviled him like the people did.  You don’t see any of them believing on Jesus right then and there.  But in Acts 18:8 and Acts 18:17 through the preaching of the cross in Corinth [1 Cor 1:18, 2:2] two rulers of the synagogue believed on Jesus.  Paul refers to Sosthenes in 1 Cor 1:1 and to Crispus in 1 Cor 1:14.  

The priests – Mk 15:31-32 – the priests mocked Jesus saying, “He saved others; himself he cannot save.  Let Christ the King of Israel descend now from the cross, that we may see and believe.”  Well, they wouldn’t have believed if he had descended.  However, in Acts 6:7, as the word of God increased, “a great company of the priests were obedient to the faith.”

Conclusion: people don’t believe because we can so skillfully argue doctrine and debate.  They believe when we lift up Jesus.  Preach the cross, 1 Cor 1:17-18.  Preach Jesus Christ crucified [1 Cor 2:2].  Lift him up.  And if you haven’t believed on Jesus Christ yet, will you believe now that he has been lifted up?