From a genuinely biblical Christian perspective, God died for the sins of all mankind--to very much include the sins of witches. What God says on witchcraft is that it is a very grave sin--really, the sin of rebellion. For us, mankind in general, to sin is to really usurp God's natural position as Lord over our own lives and to try to live without Him and His wisdom, goodness, purity, life, etc... and to do so means loss of fellowship with Our loving creator. To think that we are exempt from sin is to contradict the way God Himself really does look at us.
But there is hope. And that hope from the escape of sin lies in accepting the punishment Jesus, God's only begotten son, bore on the cross for us 2,000 years ago. By freely accepting that punishment, He provided a way for sinful man to finally stand before God--redeemed from a life of choosing to live without God.
Now, when you find in Christian history some brief examples of people taking matters into their own hands and playing "God," I submit that they didn't really understand the loving message of the cross. The Salem Witch Trials and a few of the persecutions done by "believers" over the ages are easily explained by this fact that they weren't practicing the gospel--at least not the gospel that's described in the Bible. What people commonly attack as "Christian" really isn't Christian at all... And you can be sure that God is grieved over it more than we are.
No, my friends, God Almighty loves witches. He loved (and continues to love) them so much that He paid the price for their sins... and if they ask Him into their hearts, He will forgive them and call them His very own sons and daughters. He came to set free the captives and to deliver those in bondage. He is not a Lady, and He is not a Lord... He is The Lord and There is only One God. He cares for us and He loves us with a purer love than we can ever know. I thank Him for that and for His everlasting grace and mercy.