''A few years ago, signing with a major label like this probably would have been a suicidal move,'' says Greg Graffin, 29, lead singer for the formerly underground hardcore band Bad Religion. But oh, how times change. This past August, the five-man outfit, noted for its melodic and intelligent brand of thrash, signed with Atlantic Records, thus ending 13 years as a critically acclaimed indie act on its self-owned Epitaph label. And in September, Atlantic re-released the band's Recipe for Hate, a hit by indie standards (150,000 copies sold), featuring the single ''American Jesus''-guest-starring one Eddie Vedder on backing vocals. Vedder and other like-minded, mainstream-loathing rockers have been getting Religion since the early '80s, when the punk act was launched out of a suburban garage in L.A.'s San Fernando Valley. But Graffin and the band were wary of moving into the land of corporate rock until recent breakthroughs by other alternative acts like Nirvana, Jane's Addiction, and Soul Asylum made major-label waters less alienating. ''Thanks to those bands, the majors are more sophisticated about this type of music, so there's less of a chance of us destroying our careers,'' says Graffin. Religion will do five albums for Atlantic, but don't expect any detours from their high-volume, low-maintenance sound when the quintet returns to the studio next spring. Recipe for Hate was recorded in a brisk three weeks for a puny $50,000. This time ''the budget will be bigger,'' says Graffin. ''But they can't make us use it.'' And if this foray into the major leagues doesn't work? ''We can always go back to Epitaph, so it's not so big a risk.'' Maybe not, but Graffin will play it safe and continue to work toward his doctorate in vertebrate paleontology (read: dinosaurs) at Cornell University.