Curt Schilling says his outspoken political views are keeping him OUT of the Baseball Hall of Fame ... telling TMZ Sports, "If I had said 'Lynch Trump,' I'd be getting in with about 90% of the vote."

Schilling says he's well aware he's rubbed most of the H.O.F. voters the wrong way with his anti-Obama political views ... and the inflammatory social media posts haven't helped his cause. 

FYI, Schilling was a stud for 20 YEARS -- winning 3 World Series titles with an 11-2 postseason record and a 2.23 ERA. Plus, more than 3,000 career strikeouts. 

The case for Schilling is strong ... but the ex-MLB star says he ain't sweatin' it because at the end of the day, "Life's not fair."