Masturbation and lust are not mutually exclusive. One can focus on the feelings of masturbation without lust ever entering the equation. It is a fallacy to say that masturbation always involves lust. The only way to associate masturbation as a sin is to link it to lust, which is not always involved. Like I stated before, the bible list all sort of sexual sins, if masturbation was such a sin it would be listed along with the other sexual sins. It's not fornication, it doesn't always have to involve lust, and it is not specifically stated in the bible as sin... which leads me to conclude that it is not a sin. Although, if a person thinks it's a sin and does it, then it would be a sin, if he doesn't think it's a sin and does it, then it wouldn't be a sin.