2 Thessalonians 2:15

So then, brethren, stand fast [in contrast to being shaken, as stated in verse 2], and hold the traditions which ye were taught, whether by word, or by epistle of ours. [God was doing his part in calling and in sanctifying, and so the Thessalonians are here exhorted to do their part in firmly adhering to the truth which they had believed. For if one would hold the gospel salvation he must hold the gospel truths. These truths are here called traditions; for, though inspired truths, they were as yet falling from the lips of living men, and were not yet reduced to writing, though we see by these two epistles of Paul that the New Testament record was in process of construction.]