I have seen a huge upsurge in activity by Roman Catholics and the Eastern Orthodox in trying to bring Protestants into their churches. I know of one congregation where three families have left for Orthodoxy over a short period, without warning, literally from one week to the next.
The main argument used by the internet evangelists boils down to a claim that theirs is the true church, and that we Reformed folk are called to be reconciled to our mother, Rome, or, our mother, Orthodoxy. Jesus came to found a church, they say, and here it is!
When asked to support their claim to be the one true church, the only understandable argument seems to be, “Because we say so. We are the true church to which Christ has given authority, so you had better listen up!”
So then, how do we identify the true church? What do we say to those who are strongly attracted by claims of ancient tradition, and an uninterrupted continuity of two thousand years?
The gospel itself has got to be the key to identifying a true church of Christ. So then, what is the gospel?
The gospel is the account of the birth, life, death, burial, resurrection, session, and Parousia of the Lord Jesus, the Christ – with its authorized apostolic interpretation.
Here is the interpretation: The Lord Jesus was incarnate for us men and for our salvation.
That same salvation is by pure grace, a free gift, by undeserved mercy, purchased by the cross. This gift of salvation is without reference to human works of any kind, as the apostle Paul teaches us in many unambiguous passages.
It by grace that you are saved, and this not of yourselves, it is the gift of
God, not by works, lest any man should boast. (Paul the Apostle).
Any gospel that adds works of any kind to grace is an anti-gospel, and any church that does so is an anti-church.
Application: works in our day pass by the name of free will, which is simply a way of describing what a man is able to do or work by his own power and ability. To most churches salvation is by free will, helped by grace, which is a contradiction in terms.
Therefore the RCC and EO churches have erred in setting aside the grace of God by adding works to the cross for forgiveness. Ditto all the once Protestant churches who have abandoned the gospel of free grace, such as those who follow the Billy Graham model of evangelism.
The true churches of Christ are those Reformed and Lutheran churches who steadfastly cling to the gospel of grace. Outside of this church there is no salvation, since it is there that the gospel is heard and believed, and the sacraments rightly administered – which signs and seals are ordinarily necessary for salvation as means of grace.
The is the church that is the mother of the faithful, the heavenly Jerusalem.