I was just reading through Ignatius to the Smyrnaeans. The first few chapters read almost like a creed. Here's chapter 1 in Kirsopp Lake's translation:

¹ I give glory to Jesus Christ the God who bestowed such wisdom upon you; for I have perceived that ye are established in faith immovable, being as it were nailed on the cross of the Lord Jesus Christ, in flesh and in spirit, and firmly grounded in love in the blood of Christ, fully persuaded as touching our Lord that He is truly of the race of David according to the flesh, but Son of God by the Divine will and power, truly born of a virgin and baptized by John that "all righteousness might be fulfilled by Him," ² truly nailed up in the flesh for our sakes under Pontius Pilate and Herod the tetrarch (of which fruit are we—that is, of His most blessed passion); that "he might set up an ensign" unto all the ages through His resurrection, for His saints and faithful people, whether among Jews or among Gentiles, in one body of His Church. (ISm 1)

Be sure to check out ISm 2 and ISm 3 as well. Remember, this was likely written in the very early 100's (probably before 115).