as u can see there are many different veiws on this one!!i believe that yes there is good and evil. but try asking ur friend "what rewards does he think he will get, if he does sell his soul? And who has approached him for his soul? and does he truly want bad karma? because as in someone elses post karma does exist it is powerful too,either way positive/negative.
In life it is true that sometimes we get opportunities to be bad, but that's not to say it will be best for us. Mostly it turns out that we destroys us.
i am 30 yrs old and i was born into christianity, took the wrong path at age 12, i did ouija boards, i was violent to everyone, i lost respect for myself. i stayed on this road until i was 17. then i met my man,tony. i could see that he loved me and resepected me and i changed.i i am now 30 and still with my man,with 2 kids and comparing my karma i prfer the path i'm on now xx i am a spiritualist which basically is a bit of all the religons. so i guess the question i would put to ur friend is "is ur friend wanting an average life with all its ups and downs or does he want to have a life with destruction??"
good luck xx
love & light
redsnappa