Did the Reformers believe that an apostasy had occurred?

We argue that all Christian sects are more or less apostatized from the institutions of the Savior; that by all the obligations of the Christian religion, they that fear and love the Lord are bound to return to the ancient order of things in the spirit and truth. (Alexander Campbell, Christian Baptist, vol.. 5, p.402)

We seldom hear of them [manifestations of the gifts] after that fatal period when the Emperor Constantine called himself a Christian .... From this time they almost totally ceased. .... The cause of this was not (as has been vulgarly supposed) because there was no more occasion for them, because all the world was become Christian. This is a miserable mistake; not a twentieth part of it was then nominally Christians. The real cause was, the love of man, ... was waxed cold. The Christians had no more of the Spirit of Christ, than the other heathens..... This was the real cause, why the extraordinary gifts of the Holy Ghost were no longer to be found in the Christian church; because the Christians were turned heathens again, and had only a dead form left. (John Wesley, Sermon 94)

The old time gospel, and the gifts thereof are lost. False doctrines prevail in all the churches on the face of the earth. All we can do is exhort the people to be just, fear god, shun evil, and pray. Prayer and purity may cause an angel to visit some deep depressed soul. But I tell you that within one hundred years, God will have spoken. He will restore the church again. I see a little band of people led by a prophet and a faithful leader. Some will be persecuted and burned out and murdered. From every nation shall true believers be gathered by speedy messengers. And then shall the Almighty God speak to the disobedient nations with thunder and lightning, and destruction such as men have never know before. (Christophilus Gratianus, leader of Swiss Pietism, Die Hoffnung Zions (i.e. Zion's Hope), 1732, University Library of Bazel, Switzerland)