There are only two soteriological paths because there are only two soteriological choices.
Why is so difficult for Calvinists to reject their false gospel? There could be many reasons, but the primary reason is the brainwashing that the Calvinistic cult exercises over its adherents. No matter how many Scriptures are shown which refute their false gospel, they do not make a dent in the minds of those who have been taken captive. Just like the JWs or other cults. Add to that the fact that Calvinists deliberately distort and twist many of the Scriptures, or plainly misrepresent what God has said. In all fairness we can say that The Westminster Confession of Faith is not totally wrong. But when it comes to soteriology, it fails to present the true Gospel.