The Judas book is not gospel

Callimachus:

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Gospel is condensed from Old English godspel, which is a compound meaning "good news." The first element of the Anglo-Saxon word had a long "o," but pronunciation shifted under mistaken association with God. It really is the adjective good we still use, and which the Anglo-Saxons would more or less recognize, if they could hear us say it. Then as now, it meant "having the right or desirable quality."

The Proto-Germanic root is *gothaz (cf. Old Norse goðr, Dutch goed, German gut, Gothic goþs). The original notion is "fit, adequate, belonging together," and linguists trace it back to the reconstructed Proto-Indo-European base *ghedh- "to unite, be associated, suitable." This relates our good to Russian godnyi "fit, suitable," as well as the Old English verb gædrian "to gather, to take up together," the root of gather.

It is not, however, related to God. God is good may be a theological truth, but it is not a linguistic one.

The back nine of gospel is Old English spel "story, message." This word has faded from English in this sense, but it survives as the verb spell "name the letters of." The original verb was Old English spellian, which meant "to tell, speak." The meaning "write or say the letters of a word" emerged c.1400, from the notion of "to read letter by letter, read with difficulty" (c.1300).

Spell also developed a dark side, which emerged in the modern noun meaning "set of words with magical powers, incantation, charm." This evolved in the 16th century out of an earlier more innocuous meaning "story, speech." As "Oxford Dictionary of English Folklore" notes, "The term 'spell' is generally used for magical procedures which cause harm, or force people to do something against their will -- unlike charms for healing, protection, etc."

The verb spell that means "indefinite period of time" is of uncertain origin and relationship to the other word. It goes back to Old English spelian "to take the place of," and perhaps is related to spilian "to play" (related to German spiel).

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There is much more on the attempts to translate.