Does the Bible say that witches are bad? Or is the prejudice just about Christians not respecting other human beings?

Thousands of Wiccans, who follow ancient Celtic rituals, still call Halloween by the ancient name Samhain and consider it to be the most sacred night of the year. “Christians ‘don’t realize it, but they’re celebrating our holiday with us. . . . We like it,’” stated the newspaper USA Today when quoting a professed witch.

The Bible says it because it's in the Torah. The first five books of the Bible come directly from the Torah, the primary Jewish canon of scripture. The only two verses in the Bible that contain the word "witch" are in Exodus and Deuteronomy, which are taken directly from the Torah, from Jewish scripture. 

What Christians believe, true Christians anyway, is that Jesus Christ fulfilled the old law, the law described in Exodus and Deuteronomy, the law that banned witches and said that they should not be suffered to live, and replaced it with a new law, a simpler law, a higher law, that law being: love God and love your neighbor. Jesus never says anything about witches, much less calls them "bad."

Also, do keep in mind that your idea of what a "witch" is is one largely informed by and based on European paganism. What Hebrews in the Near East 5,000 years ago were calling a "witch" was not what you as a 20th century Westerner think of when you think of a "witch." In fact, the Hebrew word used in the Bible that gets translated in some translations of the Bible as "witch" is "mekhashepha," which means magic shepherd, an innately masculine word, not feminine, and is formed out of of "mekha," meaning one who is like God," and "spepha," meaning abundance. 

Micah 5:12 says: "I will put an end to the sorcery you practice,
And no one practicing magic will remain among you."

Deuteronomy 18:9-12 says: “When you have entered into the land that Yahweh your God is giving you, you must not learn to imitate the detestable practices of those nations. There should not be found in you anyone who makes his son or his daughter pass through the fire, anyone who employs divination, anyone practicing magic, anyone who looks for omens, a sorcerer, anyone binding others with a spell, anyone who consults a spirit medium or a fortune-teller, or anyone who inquires of the dead. For whoever does these things is detestable to Yahweh, and on account of these detestable practices Yahweh your God is driving them away from before you."

Exodus 22:18 in the King James version says "Thou shalt not suffer a witch to live."

The Bible says very specifically you shall not suffer a witch to live! But then you have to go back to the origin of what the word witch and sorcerer means it's derived from the word pharmakeia. Which means to make potions out of herbs and chemicals to enslave another person essentially a drug dealer. now friend if I was going to be a witch and deal with herbs and potions I would get rid of the stigma of calling myself a witch or a warlock or sorcerer or wizard I would go to the business license department and I would get myself a license to be herbal healer! And I would advertise myself as a herbal healer. The difference between a street drug dealer and a pharmacist is a piece of paper one way you're a criminal and despised the other way you're respected man with a license to dispense medicine

Witches are doing evil they are trying to have power more then trying to seek Jesus Christ for help depend on Jesus Christ for help would be a lot better then trying to cast a spell wouldn’t you think seek the lord while you can, after we are gone we cannot seek the lord any more can we

They can be said to worship false gods which is against the Commandments and therefore bad.