In this passage, as earlier in verse 25, we continue to have problems with respect to the tense. The printer’s manuscript (the earliest textual source for this passage) has the present-tense forms come and become. The 1830 edition changed the come to came, and this past-tense form has been maintained in the text ever since. On the other hand, the present-tense become has been retained except for the 1906 LDS large-print edition.
There is evidence that Oliver Cowdery frequently mixed up come and came in the manuscripts (for an extensive list where he wrote come in place of came, see under 3 Nephi 4:22). Here in Moroni 7:26, the difficulty with come is twofold: (1) the following independent clause is in the past tense (“men also were saved”); and (2) if come were correct, we would expect the indicative form cometh or comes, not the subjunctive come. It is not surprising that the 1830 typesetter emended come to came.
On the other hand, the use of the present-tense become in the following clause does not seem inappropriate. However, the parallelistic use of by faith suggests that the past tense should occur throughout:
The 1830 typesetter placed a semicolon between these two independent clauses, thus separating the second clause from the first one, even though both have by faith. Yet the two clauses are closely connected, and a comma shows a closer connection than a semicolon.
There is no direct evidence in the manuscripts of mix-ups between become and became in the simple past tense. In 4 Nephi 1:43 there is some indirect evidence that Oliver Cowdery (the presumed scribe in 𝓞) may have written became in 𝓞 so that it appeared more like become (for discussion, see under that passage). There are, to be sure, some mix-ups between become and became as the past participial form for the verb become (for this, see under 1 Nephi 17:43).
It should also be noted that the New Testament epistles clearly allow for men to become the sons of God while still in this life:
Thus there is nothing wrong with the text in Moroni 7:26 claiming that by faith men became the sons of God while they were yet alive. The future-like use of become in the current text for Moroni 7:26 is not necessary and, based on the past-tense usage in the conjoined preceding clause, is probably an error for became. In order to better show the parallelism between the two independent clauses, both of which use the phrase by faith, the semicolon between the two clauses will be replaced by a comma in the critical text.
Summary: Maintain in Moroni 7:26 the past-tense came in the after- clause (“and after that he came”); parallelism between the two following main clauses argues that the past tense should occur in both of those clauses (“men also were saved by faith in his name and by faith they became the sons of God”); these two main clauses should be separated by a comma rather than by a semicolon.