In 1751 he became a priest, in 1753 Archdeacon of the main church in Wolfenbüttel. In 1766 he became general superintendent and the first preacher in Wolfenbüttel and in 1776 general superintendent in Brunswick. After receiving work in the main church of Wolfenbüttel Knittel started to examine manuscripts housed in the Ducal Library of Wolfenbüttel. In 1756 he studied the Codex Guelferbytanus 64 Weissenburgensis. The manuscript and its palimpsest text had earlier been examined by Heusinger, who described it in 1752, but Knittel was the first who recognized that the palimpsest Greek text belonged to two different manuscripts of the New Testament. Knittel designated these two texts by sigla A and B. He recognized also lists of the κεφαλαια as another, the third Greek manuscript. Knittel also deciphered and reconstructed the Gothic-Latin text of the palimpsest and published it in 1762 at Brunswick. It is known as Codex Carolinus. The upper text of palimpsest contains text of Isidore of Seville's Origines and his six letters. Knittel designated it by siglum E and dated it to the 11th century. Knittel made many errors in deciphering the palimpsest's text, especially in the Latin text of Codex Carolinus. Tischendorf made a new and more accurate collation for the Latin text. A new collation of the Gothic text was published by Carla Falluominiin 1999. Knittel examined also other manuscripts. Knittel defended a traditional point of view in theology and was against the moderntextual criticism. He defended an authenticity of the Pericopa Adulterae, Comma Johanneum, and Testimonium Flavianum. According to him Erasmus in his Novum Instrumentum omne did not incorporate the Comma from Codex Montfortianus, because of grammar differences, but used Complutensian Polyglotta. According to him the Comma was known for Tertullian.
Works
Gedanken von einem Lehrgebaude einer gemessenen Geistlerlehre und ihrem Bussen in der Gottesgelahrtheit 1746
Epistola, in qua de eo, quod in Georgicis Hesiodes, quae εργα και ημεραι inscribuntur, supposititium est, disseruit de salis vallibus et a viro celebrrimo in arte critica M. horum, quae accusantus, vindice atquae assertore, dissentit, Brunsvick 1754
Neue Gedanken von den allgemeinen Christsehlern in den Handschriften des Neuen Testamtns u. s. w., mebst einem Versuche einer hermeneutischen Muthmassunge - Sitten - Lehre der ersten Kirche, Braunschweig 1755
Praecopium Ulphilanum primum, Brunovici 1758; alterum 1760
Ulphilae versionem Gothicam nonnullorum capitum epistolae Pauli ad Romanos e litura MS. rescript Bibliothecae Guelferbytanae, cum variis monumentis ineditis eruit, commentatus est, detitque foras, Brunovici 1762
Neue Kritiken über das weltberühmte Zeugnis dea alten Juden Flav. Josephus von Jesu Christo Braunschweig 1779
Neue Kritiken über den berühmten Sprych: Drey sind, die da zeugen im Himmel, der Vater, das Wort, und der heilige Geist, und diese drei sind eins Braunschweig 1785
Ueber die Aufklärung des Lachmannes, Frankfurt und Leipzig 1787
