Mosiah 26:5–6 Textual Variants

and now in the reign of Mosiah they were not half so numerous as the people of God but because of the dissensions among the brethren they became more numerous [ for 1|For ABCDEGHKPRST|And FIJLMNOQ] it came to pass that they did deceive many with their ﬂattering words which were in the church and did cause them to commit many sins

The 1852 LDS edition replaced the conjunction for with and. This substitution appears to be accidental. The original for was restored to the LDS text in the 1920 edition, undoubtedly by reference to one of the early editions. The for is necessary because it explains that the dissenters became more numerous as a result of their effective (but deceitful) proselyting methods.

Summary: Maintain the conjunction for in Mosiah 26:6, which is used to explain why the dissenters were so successful in gaining adherents.

Analysis of Textual Variants of the Book of Mormon, Part. 3

References