They called Him by Names-Beelzebul

Luke 11:14-28
New International Version (NIV)
Jesus was driving out a demon that was mute. When the demon left, the man who had been mute spoke, and the crowd was amazed. But some of them said, “By Beelzebul, the prince of demons, he is driving out demons.” Others tested him by asking for a sign from heaven. Jesus knew their thoughts and said to them: “Any kingdom divided against itself will be ruined, and a house divided against itself will fall. If Satan is divided against himself, how can his kingdom stand? I say this because you claim that I drive out demons by Beelzebul. Now if I drive out demons by Beelzebul, by whom do your followers drive them out? So then, they will be your judges. But if I drive out demons by the finger of God, then the kingdom of God has come upon you.
“When a strong man, fully armed, guards his own house, his possessions are safe. But when someone stronger attacks and overpowers him, he takes away the armor in which the man trusted and divides up his plunder. “Whoever is not with me is against me, and whoever does not gather with me scatters. “When an impure spirit comes out of a person, it goes through arid places seeking rest and does not find it. Then it says, ‘I will return to the house I left.’ When it arrives, it finds the house swept clean and put in order. Then it goes and takes seven other spirits more wicked than itself, and they go in and live there. And the final condition of that person is worse than the first.” As Jesus was saying these things, a woman in the crowd called out, “Blessed is the mother who gave you birth and nursed you.” He replied, “Blessed rather are those who hear the word of God and obey it.”

You must know that even though the Lord Jesus Christ isn't present on earth physically, His ministry on earth is still alive the same way when it was when He was present in body. When you speak against Him, that means you are no different from those above who called Him names.