The difference mattered

How much weight should you put on similarities in doctrine when you have got this kind of difference as well?

The sum and substance of the great charge which the Reformers adduced against the Church of Rome was, that while she proclaimed to men with a considerable measure of accuracy who Christ was, and what it was that He had done for the salvation of sinners, she yet perverted the gospel of the grace of God, and endangered the salvation of men's souls, by setting before them erroneous and unscriptural views of the grounds on which, and the process through which, the blessings that Christ had procured for mankind at large were actually bestowed upon men individually, and of the way and manner in which men individually became possessed of them, and attained ultimately to the full and permanent enjoyment of them.

William Cunningham, Historical Theology Vol. 2, p. 3