How were the witchcraft linked to the devil?

Answer 1

It wasn't. There is absolutely no connection.

The Christian faith pressed that if you worshiped any other religion than Christianity, you were a pawn, follower, and worshiper of Satan.

Answer 2

One thought:
In the online dictionary, 'Religion' is described as "a particular system of faith...an interest to which someone ascribes supreme importance"; and a 'Witch' is defined as 'a follower or practitioner of modern witchcraft (Wiccan priest or priestess)". Under these definitions, witchcraft could certainly be called a religion.
Biblically speaking, it is felt by some experts in the field, that witchcraft, magic, sorcery, exorcism and Astrology are all components of ancient Babylon's pagan religion, beginning with Nimrod (Genesis 10:8-10/Genesis 11:9)which thrived and spread among much of humanity after the flood of Noah's day. Historically, Babylon is known to have been rife with idolatry, divination, magic and temples dedicated to Marduk(Merodach), and pagan gods and goddesses of all sorts. Daniel dealt with 'magic-practicing priests and conjurers' when he was in Babylon (Daniel 4:7). Many feel that one who claims to be a witch often centers devotion on 'the creation' rather than the 'creator', whether it be things, persons or spirit creatures, often using spiritistic supernatural powers, condemned in The Bible, in their worship.(Deuteronomy 18:10-13/Jeremiah 50:1,2 +38/Romans 1:18-25)