Is Satan a real, living being? If he is not then Jesus spoke to and was tempted by a non-existing entity.
Jesus spoke quite a bit about the devil, demons, and Hell, so if these things are not real then it is all nonsense, however, Jesus was not know to be nonsensical.
Satan is the enemy, the adversary, the accuser of the brethren. To whom is the devil the enemy of? To God, to all of Heaven, and to God's children.
If God is real, and I believe that He is, then Satan must also exist. We often see the results of Satan's work on the news and in life all around us, in fact if we are not careful, we will be guilty of missing the work of God all around us too.
What do you think? Is Satan real? Is the work of Satan evident in our world today?