A demon who might want to corrupt a woman won't start by asking for her soul. To corrupt her he might start by giving her some power without asking anything in return.

Even today there are still Christians who consider certain New Age practices immoral. Hypnosis doesn't involve summoning the devil and making a bargain with him. It's still considered to be a dark practice by many Christians. The catholic church took till 1956 to accept hypnosis as not being immoral.

Genemanipulated food would be a modern example where some Christians object that the practice is violating "natural law". Craig Venter has to defend against the charge of playing God. According to that Christian perspective biologists are supposed to study how nature works instead of changing it.

Similar things are true for opposition to cryonics. The person who get a contract with Alcor isn't a Satanist. He still sins, by trying to escape God's plans for how human's are supposed to live.