how did luke know that jesus said god forgive them they not knowing what they doing?

That's right, he wasn't personally present to witness the crucifixion, and that detail is unique to his account. So it's a valid question.

The author is the same as the one for the book of Acts, and both accounts are addressed to Theolphilus, and one refers to the other. Paul's dear friend, Luke the doctor, is the author in question. He was a Gentile by birth, was well educated in Greek culture and a physician by profession. He was a companion of Paul at various times but Paul did not witness the crucifixion either. So, where did Luke get his info from?

At the very start of his gospel he tells us. He speaks of various other accounts of Jesus' life and death. He says he personally investigated, using personal eye-witness accounts. That's in the first 4 verses. The gospel was written between AD 59 and AD 80, well within the life-time of all of the apostles. So Luke would hear the details about Jesus' death from the apostle John, Mary (the mother of Jesus) Mary Magdalene and Mary the wife of Clopas who were named as being present. And even some of those who jeered at Jesus and were not followers of Jesus at the time of his crucifixion, might have become Christians after Jesus' resurrection. Even the centurion in charge of the crucifixion was moved to declare Jesus to be the Son of God. If he later became a Christian, his testimony would have gone round all of the churches.

There were no lack of eye-witnesses and, after the resurrection, when Christians began to make sense of the events, they would recollect as much as they could about what Jesus had said. Luke gleaned his info from such eye-witnesses. AiH

I think Luke talked to people, a sort of interview situation. You see, Luke was a sort of contemporary historian. I think he wrote the Acts of the Apostles as well. He wasn't there to see all of what happened in Acts or with what was written in the Gospel according to Luke. He got around. Luke is an outsiders Gospel; the contemporary historian that people complain that isn't there. Since it is included in the Bible, the antichrist critics will never count that work as a contemporary historian's writing. Yet there it is.

Also I find it interesting that Paul wasn't there either. He didn't come on until after Jesus' ministry. So look at what he talks about in Acts 13. He wasn't there, how did he know? And from what I have seen, his testimony sounds a lot like the timeline in John's Gospel.

Acts 13:23-41

http://www.biblegateway.com/passage/?search=Acts%2...

Then said Jesus, Father, forgive them; for they know not what they do. And they parted his raiment, and cast lots.

Luke 23:34 (KJV)

How do you know Luke was not there, Luke could have been one of the other 70 disciples that Jesus taugh and sent out. Jesus always sent his disciples in two's. Use your ability to read between the lines, to comprehend things unsaid by things that have been said.

And he called unto him the twelve, and began to send them forth by two and two; and gave them power over unclean spirits;

Mark 6:7 (KJV)

After these things the Lord appointed other seventy also, and sent them two and two before his face into every city and place, whither he himself would come.

Luke 10:1 (KJV)

If Judas committed suicide who did Jesus send with the 11th to send them by two's?

Did Jesus pair the 11 with 11 from the other 70 disciples? Do you know?. No, all you know for sure is that they were all sent by two's, not in three's or by themselves but they were sent in pairs of two.

Peter was there, Bartholomew was there, Philip was there, James was there, Andrew was there, but these were all hiding far off. John was there, Mary mother of Jesus was there, Mary sister of Martha was there, Marha was there, Salomone was there, Mary Magdalene was there, Nicodemus and others were all there at the cross, so who is to say Luke was not there?

Yes, there are other gospels that state there were other apostles present when Jesus died on the cross, Bartholomew who was an apostle wrote about the things he saw while he watched Jesus dying on the cross from far away. You should read it.

John was likely the only one to author his own Gospel. The other three, the synoptics were probably written "in the tradition" of each of their accounts. So, while the writers of the synoptic Gospels knew what they did by oral transmission, Luke would likewise have learned of what Jesus said from the first-hand witnesses of the crucifixion, whether that be from John, Mary, Mary, or anyone else who was there.

Of the oldest 5,500 texts, ranging from the 3rd to the 10th centuries, not a single copy is identical to any others. Though most changes are contextually insignificant, some are VERY significant -- such as two of the oldest texts available - written in the language of the day - Koine Greek - that say that the one called "son of the father" (bar abba) did not die on the cross, but was released unharmed.

Pssst. I have a hint for you Luke interviewed the people who were eye witnesses and wrote an article for Newsweek Magazine.

He didnt know because he wasn't there, the bible probably just made something up