Father, Forgive Them

What happened next?
34 Then Jesus said, “Father, forgive them, for they know not what they do.” And they divided His garments and cast lots. 35 And the people stood looking on. But even the rulers with them sneered, saying, “He saved others; let Him save Himself if He is the Christ, the chosen of God” (Luke 23:34-35). 

When Jesus said, "Father, forgive them, for they know not what they do" (Luke 23:34), whom was He asking the Father to forgive?
It could have been one or both of the robbers who were on the crosses next to His and "reviled Him" (Matthew 27:44, see Criminals on the Cross), although their crimes paled in comparison to what the others just had done to Him. He  also could have been asking the Father to forgive the four Roman soldiers who had stripped Him naked (See King of the Jews), nailed Him to the cross, and divided "His garments" (Luke 23:34). He also could have been asking the Father to forgive everyone else involved in His arrest, torture and crucifixion, including "the rulers" (Luke 23:35) who sneered at Him, saying, “He saved others; let Him save Himself if He is the Christ, the chosen of God” (Luke 23:35).

"Father, forgive them for they know not what they do" sounds like a defense of His enemies. Why would Jesus say this all of a sudden?
There could have been more going on in the spiritual realm than we realize, and Jesus could have been responding to prosecution; now that He hung from the cross - since all that the Jews and the Romans had to do for their part was done - perhaps some among the "more than twelve legions of angels" (Matthew 26:53, see Malchus) may have started begging the Father to let them go and shred those who had trampled their Lord. In any case, consider things from the Father’s perspective. He already had to to decline His innocent Son when He asked Him while sweating blood, “Father, if it is Your will, take this cup away from Me" (Luke 22:42, See John 18). He watched His Son get mangled into a bloody pulp. Now perhaps His angels are crying out to Him to let them unleash their fury on the Jews and the Romans. But then, from the cross, Jesus - the Prince of Peace - asks Him, "Father, forgive them, for they know not what they do." At that, maybe the angels crumbled to their knees and began to weep, the lips of the Father quivered and He whispered under His breath “My Son…” But here is the clincher: the Father then had to pour the sins of millions of sinners into that very Son, turning Him into sin itself - "For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him" (2 Corinthians 5:21) - and hear His desperate cry, "Eli, Eli, lama sabachthani?” that is, “My God, My God, why have You forsaken Me?" (Matthew 27:46) as the Holy Spirit is withdrawn, and the death penalty is carried out. This is the ground zero of the Bible, where the justice of God - the need for sin to be punished - collided with the mercy of God - His desire to save us from that punishment. And the only one capable of bearing all of that sin and absorbing the force of that collision was His sinless only Son.

Why did He do this?
Because He loves us. The God of eternity, the Creator of the universe, loves us - specks of dust on a speck of dust in one corner of His universe - so much that He chose to go through this agony for us instead of just wiping us off the earth. This is why God is called the God of love, because He loves us more than we can imagine, more than we love ourselves, far more than we deserve.