"This is the generation of the great LEVIATHAN, or rather, to speak more reverently of that mortal god, to which we own under the immortal God, our peace and defense." -Thomas Hobbes: Leviathan
It seems to me that there is a common confusion with regards the Protestant doctrine of the “Invisible Church”, especially in the Anglophone world, due to an unfortunate shift in meaning in the term as it occurred in the English Reformation.
The concept of the “Invisible” Church as it began in the Magisterial Reformation did not actually refer to any electoral list but to the “inward” or “spiritual” condition of the believers. Whereas by the time of the Westminster Confession in 1646, the idea of the “Invisible Church” has become more or less identified with sum of the elect gathered under Christ or in the words of the confession, “The catholic or universal Church, which is invisible, consists of the whole number of the elect”, the Magisterial Reformation understood the “Invisible Church” to refer not to the elect, in contrast to the reprobate, but to the true believers from the heart who are truly united to Christ by faith. This inward spiritual union of believers in the heart which constitutes the “invisible Church” is in contrast to the “outward” or “visible” Church consisting in outward membership within a canonical polity or organisation.
This contrast can clearly be seen in a draft document by Thomas Cranmer after his meeting with the Lutheran divines which he intended for King Henry VIII but later abandoned in the 1530s. The article on the Church reads:
In the Scripture, the word “Church” has two main meanings, apart from others; one of which means the congregation of all the saints and true believers, who really believe in Christ the Head and are sanctified by his Spirit. This is the living and truly holy mystical body of Christ, but known only to God, who alone understands the hearts of men. The second meaning is that of the congregation of all who are baptised in Christ, who have not openly denied him nor been lawfully and by his Word excommunicated. This meaning of “Church” corresponds to its status in this life in that in it the good are mixed with the evil.
Thus, it is this failure to recognise that the invisible or “hidden” Church as a spiritual communion of faith in the heart as opposed to an electoral list in God’s mind which has been the source of a lot of confusion in Anglophone ecclesiology. The “invisible Church” is not in contrast to the reprobate but to the empirical or visible Church of those who outwardly profess faith in Christ and are part of some empirical canonical polity. Thus while those who are “inwardly” true believers would seek out Christian fellowship and be part of a canonical polity or congregation, but not all who are “outwardly” Christians are necessarily believers from the heart for the hypocrites are mixed with the true believers, etc. Therefore as opposed to the empirical Church, the true Church is essentially a communion of faith in the heart sharing the same hope and in love and charity with each other as opposed to being in mere canonical or legal fellowship, etc.