Damn, it’s like they don’t want you to get at the raisins. There must be a better way… You either mutilate the bag and your fingers, or cut it with scissors (or a knife - not recommended lol) , either way can’t be resealed without additional apparatus
The trick is to control the angle at which the tear meets the side of the bag. With a large enough angle, it won’t easily rip down the side of the bag unless you force your hand into the hole or something.