Here the 1874 RLDS edition replaced the determiner the with a in the phrase “the knowledge of the Lord”, thus giving “a knowledge of the Lord”; the original the was restored to the RLDS text in 1908. Usage elsewhere in the text supports both the and a in the phrase “to bring someone to the /a knowledge of X”, with 20 occurrences with the and 4 with a. When X refers to the Lord, we have 7 other occurrences with the:
But in one case, a is found in the earliest text:
In each case of “to bring someone to the/a knowledge of X”, we let the earliest textual sources determine the reading for the determiner of knowledge.
Summary: Accept in Alma 23:5 the earliest reading, “and thousands were brought to the knowledge of the Lord”; the use of the before knowledge is supported by the clear majority of examples elsewhere in the text.