1 Cor. xv. 3-8. References by a preacher to what he has taught to any whole congregation must, almost of necessity, be references to what he was in the habit of teaching. The articles mentioned here are part of S. Paul's Creed, viz. the articles which he is about to use as the basis of an argument about Resurrection.
Acts xix. 2, 3. The ignorance about the Holy Spirit displayed by the 12 men at Ephesus revealed to S. Paul that they had not been baptized as Christians; for (S. Matth. xxviii. 19) that would have involved Teaching about the Holy Trinity.
Acts viii. 37. This verse, though not now believed to be part of the original text, was so believed by Irenaeus (A.D. 170).
It therefore shows us that a confession of faith at Baptism was (1) expected in Irenaeus' time, (2) expected by someone much earlier, who being accustomed to it, wrote it in the margin, or between the lines of a copy of the Acts.
2 Tim. i. 13, 14. The form of sound words was a good deposit which Timothy was to hold fast.
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There are other passages which contain references to the Holy Trinity: suggesting that the earliest Christians, when thinking of the Godhead, were prone to include the Three Persons, as we by reason of our Creeds are also disposed to do. Thus our investigation leads us to suppose that a Creed was early used as a Basis of Teaching, and as a Password at Baptism: that it soon settled down into a form very like the Apostles' Creed: that in A.D. 325 the controversy about our Lord's Divine Nature led to the expansion of those Articles which referred to Him.
To these we may add that in 381 the Council of Chalcedon expanded the Article I believe in the Holy Ghost, or formally adopted an expansion which had become usual: and so gave to the Nicene Creed the form which it now has.
It is difficult to say exactly where the Apostles' Creed is most likely to have come as a link in the historic chain.
A comparison may be usefully made between: