Let’s look closely at this portion to see if we can find the answer to your good question.  We read in Luke 23:33-34, “And when they were come to the place, which is called Calvary, there they crucified him, and the malefactors, one on the right hand, and the other on the left. Then said Jesus, Father, forgive them; for they know not what they do. And they parted his raiment, and cast lots.” 

We can say here that forgiveness was sought after and offered to those who crucified the Lord Jesus.  What a touching scene!  Even as the people were crucifying the Lord Jesus, He was praying for their forgiveness.  This is fulfillment of a prophesy concerning the Lord Jesus in Isaiah 53:12, “Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he hath poured out his soul unto death: and he was numbered with the transgressors; and he bare the sin of many, and MADE INTERCESSION FOR THE TRANSGRESSORS.” 

Notice that in the words of the Lord, even though He declared them ignorant…forgiveness was still needed.  What were they ignorant of?  Certainly, they knew they were killing an innocent man…and that’s murder.  If the Jews had only opened their eyes, they would have realized they were murdering the true Son of God, but in their rejection of Him, they refused to see who He was.  Perhaps they were ignorant of the severe consequences they were bringing upon themselves.  However, they were guilty of this dire sin as we read in Acts 2:23, “Him (Christ), being delivered by the determinate counsel and foreknowledge of God, YE HAVE TAKEN, AND BY WICKED HANDS HAVE CRUCIFIED AND SLAIN.”

The Lord did offer forgiveness to these evil, God rejecting men.  Acts 17:30-31 says, “And the times of this ignorance God winked at; but now commandeth all men every where to REPENT: Because he hath appointed a day, in the which he will judge the world in righteousness by that man whom he hath ordained; whereof he hath given assurance unto all men, in that he hath raised him from the dead.”  God was willing to forgive these people IF they would repent of their sins in their acceptance of the Lord Jesus.  However, as a whole, the Jewish nation continued to reject the Lord and are still in a state of rejection even to this very day.  As such, they are not held guiltless.  They are not forgiven because they had not sought the forgiveness of God. 

Does God forgive the “ignorant heathen” and allow them into Heaven without knowing Christ as their savior?  No, He does not, for none can claim ignorance regarding the existence of God.  Let’s consider what we read in Romans 1:19-21, “Because that which may be known of God is manifest in them; for God hath shewed it unto them. For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that THEY ARE WITHOUT EXCUSE: Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.”  The Lord reveals Himself to us through His glorious creation.  Sadly, many refuse to recognize God and do not glorify God.  To acknowledge that God exists and there is only one God is not salvation.  But acknowledging that, one can continue on the exercise faith in the Son of God for his salvation. 

What about those who have never heard of the Lord Jesus?  We often say that “A seeking savior and a seeking sinner will soon meet.”  If someone has a desire to know God, the Lord will make sure that person is shown the proper way of salvation.  For a couple of examples of this, read about the Ethiopian Eunuch who wanted to know the Lord, so the Lord sent Philip to him. (Read Acts 8:26-40.)  Read also about Cornelius, an Italian centurion, who longed to know about the Lord, so the Lord sent Peter to him.  (Read Acts 10). 

The Lord does not forgive sin without a basis to forgive.  He has provided a way for all to be forgiven, saved, and made a part of the family of God…and that is through faith in the Lord Jesus Christ.  Christ Himself said in John 14:6, “…I am the way, the truth, and the life: NO MAN COMETH UNTO THE FATHER, BUT BY ME.”  (CC)  (570.6)