Roman Catholicism
At what point in its history can we say that the Roman Catholic Church had officially pronounced dogmas that are unscriptural that it may be considered to have essentially stopped being THE church of Jesus Christ, or THE New Testament church? (In our church -- an evangelical Protestant church-- we pray the Apostles' Creed, including the phrase "I believe in the Holy Ghost, the holy Catholic church, the communion of saints, etc." (i.e., the Nicene Creed)to express our link to the apostolic church. This makes many of our Roman Catholic attenders comfortable. However, very seldom is it explained in our pulpit the essential differences between the Roman Catholic and the evangelical Christian faith.)
--Tom Matic
I am uncomfortable attempting to pinpoint a date when the Roman Catholic church apostatized, since that apostasy was so gradual. The post-apostolic church began incorporating unbiblical beliefs and practices almost immediately after the apostles passed away. Heretical teaching about the ransom-to-Satan theory of redemption, the institution of New Covenant priests and city-wide bishops, erroneous practices of church discipline, etc., all made their way into the church early on. However, the central truth of the gospel remained intact for quite some time after all this.
As for your question about just when the Roman church ceased to be THE church of Jesus Christ; well, it never was. The church is not something that is defined by geography or denominational affiliation. Members of the body of Christ could (and still can) be found within the Roman Catholic church--but there was never a time when the Roman Catholic church WAS the church of Jesus Christ. As for official dogmas that separated Roman Catholicism from the truth of the gospel, I would have to point to the Council of Trent during the Counter-Reformation of the sixteenth century. Until Trent, Roman Catholic believers could, with a good conscience, believe in salvation by grace through faith in Christ apart from works. Trent officially condemned the biblical concept of salvation. There are still many Roman Catholics who do not understand the official teaching of Rome and do not hesitate to express their faith in Christ alone for their salvation.
As for the Apostles' Creed--there is nothing inherently objectionable in the creed itself, although Roman Catholic interpretation of the creed is certainly objectionable ("one holy catholic church" is interpreted to mean "Roman Catholic church," and "the communion of saints" is interpreted to mean that we may pray to the saints). The Roman Catholic attendees of your church would probably not feel uncomfortable if you simply omitted the creed altogether, since these attendees are not likely staunch Roman Catholics. Staunch Roman Catholics who understand the teaching of Rome would never attend a Protestant church because it is strictly forbidden by Rome to do so.
E.S.