Joanne Case suggests (personal communication, 14 September 2004) that the indefinite article a in the second instance of “to obtain (a) forgiveness” might be in error; that is, as Joseph Smith dictated the text to Oliver Cowdery, an extra a was inserted. Of course, there is the possibility that the first instance may have originally read “to obtain a forgiveness” and that the a there was lost. In both cases, the original manuscript is extant, so the difference is found in the earliest source.
Elsewhere in the text, the noun forgiveness is never preceded by the indefinite article:
The normal expression in modern English is without the a. However, there are instances in the history of English of a forgiveness, as in the following examples (accidentals simplified) taken from the online Oxford English Dictionary and from Literature Online :
Given this evidence for a forgiveness, the critical text will retain the unique instance of “to obtain a forgiveness” in Alma 39:6. In the original text, there are a number of nouns which unexpectedly take the indefinite article a. For three examples, see under Alma 32:6.
Summary: Maintain in Alma 39:6 the unique occurrence of a forgiveness, the reading in 𝓞; elsewhere forgiveness occurs without any indefinite article, including one instance earlier in this same verse.