IMO, inconsistency can be OK on matters of less than salvific importance.

But not with regard to the Gospel, and, hopefully, not on other core teachings of Scripture either.

Examples of both:

* Depending on whether you see the New Covenant as a continuation of the Old, or a superior replacement to the Old, you will logically come to different conclusions about ecclesiology, eschatology, and infant vs. believer's baptism. But you can still hold to all the core tenets of the historical, Biblical, Reformed Christian faith either way.

* Semi-Pelagianism, continuationism, evolution, the LGBTQP movement, and Marxism are all direct attacks against biblical teaching, and at least indirectly against the Gospel, and I question whether a saved, Spirit-filled person can believe in any of these. The kind of "blessed inconsistency" described by Sproul may well be the only hope for the proponents of these kinds of things. Most pertinently to this discussion: continuationism says that God continues to speak today, outside of His Word; that is a fundamental repudiation of the authority, sufficiency, finality, and pre-eminence of Scripture. Even among those who are otherwise Calvinistic in their soteriology, there are those who fail to see this. Such people IMO have one foot in the door of Christianity, and the other in the world of paganism. It is impossible for me to tell in the general case which foot they are truly trusting in.

Aspiring student of Christ