Who was Saul persecuting? How can that be? Jesus was and is in heaven - right? As if coming from the mouth of a confused person, "yes and no".
Jesus did ascend and resides in heaven, however the Spirit of Jesus, the Spirit of God resides in us, his disciples, here on the earth. There is more to that picture, but let's look at the question of Jesus. "Saul, why do you persecute me?" To persecute is to harass or to systematically harass. How was Paul doing this? It was Stephen who was martyred and many others dragged into prison. You see where this is going.
Jesus said, if you give a cup of water to someone in my name, you have given it to me. So that would mean that if we harass someone, speak ill of someone, without love reprove someone, we are doing it to Jesus. After all, Jesus didn't drink the water, the person did. This would strictly apply to believers, however the image of God is in everybody.
Paul in the last few chapters has been beaten and almost killed several times precisely because of what He believed. The Jews are trying their best to silence the voice that is disagreeable to their own by killing him. We may not physically kill, but how about our words? What are they designed to do, bless or cure, encourage or defame?
It is so easy to criticize. So easy to disagree without grace. In a world that is full of harassment let's all rise above it. Let's resist harassing anyone - which is no easy task. Some are so easy to harass! But you can do it. You were made to love.