An expression that was current in Mr Darby’s time was ‘Jewish church’. I googled the expression, and the only relevant information was on Jews in the church. So whilst the error is not widespread now (except in the way that public Christianity has been judaised), a short paraphrase of part of Darby’s paper on ‘Law’ would be useful.
Start with the truth. The Church, the body of believers, never existed till the Holy Spirit came forty days after Christ’s ascension. It could not exist till its Head, had been exalted as Man having accomplished redemption. When exalted, God ‘gave Him to be Head over all things to the Church, the fulness of Him who filleth all in all’. (Eph 1:22-23.) He has made both [Jew and gentile] into one new man, a habitation of God in the Spirit (see Eph 2:14-22). Only now is the church known to the principalities and powers [i.e. angels][*] and they see the manifold wisdom of God. Before then, men were not built together for a habitation of God through the Spirit. The entity did not exist.
The idea of a church transcending dispensations is false. There was no collective expression of faith until the establishment of the Jewish nation, and persons were in that by birth and not faith. It was not faith that united the Jews, it was their descent from Jacob. Physical circumcision was the witness to a (male) person’s position. Now we see this idea being introduced into Christianity, with baptism replacing circumcision. Salvation is not the Church, nor the Church salvation. Conscience, faith and consequently salvation and sonship are all individual. The church is formed of those who have been saved, those with faith. They are baptised by one Spirit into one body. ‘The Lord added to the church daily such as should be saved’ (Acts 2:47). That is how the church started.
Original Article ‘Law’ – Collected Writings Vol 10 Doctrinal 3 p1
[*] [xxx] signifies my clarification