Pieper: The Open Heaven, Part 5 (Deniers of Grace Alone)

In Part 4 (Table of Contents in Part 1), Pieper points out how Calvinists close the doors of Heaven by deny universal grace, but now he goes on to a much larger kettle of fish – those who deny Grace Alone (sola gratia)(page 272):

However, the wretched business of closing heaven is carried on in even wider circles. Heaven is actually closed to the sinner by all those who teach that, while divine grace has been secured by Christ for all men, yet this grace, proclaimed and proffered in the Gospel, together with the gracious operation of the Holy Ghost which produces faith in this Gospel, is not sufficient to insure heaven, since salvation must be earned in part by man's own works, efforts, and merits.

Pieper goes on to name 3 groups who close Heaven by deny the doctrine of sola gratia or by Grace Alone.  The first 2 are:

1) Roman Catholic Church 

This is the teaching of the Roman Catholic Church. The Roman Church erects a barrier in front of the gate of heaven opened by Christ's perfect atonement by demanding that all who want to enter that gate must first give proof of their fulfilment of the "Law of God and the commandments of the Church." This false doctrine is expressly taught in the chief confession of the Roman Catholic Church, the Decrees of the Council of Trent. (Cf. Sessio VI, Can. 20.) Rome even goes so far as to anathematize all who put their trust solely in the mercy of God according to which He forgives all sins for Christ's sake. (Can. 12 and elsewhere.) Scripture, however, decrees in unmistakable terms that this mandate excludes men from heaven: "Christ is become of no effect unto you whosoever of you are justified by the Law; ye are fallen from grace." Gal. 5: 4; and again: "As many as are of the works of the Law are under the curse," Gal. 3: 10.

2) Arminians

... the Arminians ... insist that God's grace in Christ is not sufficient to convert and save the sinner; for man himself must cooperate in his conversion by means of those spiritual powers which he has retained even after the Fall. The specific error of Arminianism is that divine grace cannot exert its power without the cooperation of man's free will.

The Wikipedia article on Arminianism explains that Methodists, Congregationalists, and certain Baptists hold to this doctrine.  But their comparison chart of various "Protestant" denominations has an error on it and this error is covered by Pieper's presentation of the third group that denies "by Grace Alone" and it is a bit of a surprise.  I will cover them in Part 6 – "Lutheran" deniers of sola gratia.