By Craig Fisher

The conjunction כִּ֖י is used in the Old Testament 4481 times. It is translated in the NASB into over 60 different English words. It is very difficult to make a theological point depending on this conjunction. Although the most common use of כִּ֖י is translated “because.” This is called the causal use.

1 Samuel 2:25
Notwithstanding they hearkened not unto the voice of their father, because the LORD would slay them.

This could also be translated as a concessive or emphatic use of כִּ֖י

1 Samuel 2:25
Notwithstanding they hearkened not unto the voice of their father, therefore the LORD would slay them.

This is supported by the two commonly used references of Hebrew: Gesenius’ Hebrew grammar The Brown, Driver, Briggs Hebrew And English Lexicon.

The absolute certainty with which a result is to be expected is emphasized by the insertion of כִּ֖י
Gesenius, Wilhelm, E. Kautzsch, and A. E. Cowley. 1910. Gesenius’ Hebrew grammar. Oxford: Clarendon Press. P. 498

Example
Isaiah 7:9 King James Version (KJV)
If ye will not believe, surely ye shall not be established.
אִ֚ם לֹ֣א תַאֲמִ֔ינוּ כִּ֖י לֹ֥א תֵאָמֵ

The causal use would be translated “ye will not believe, because ye shall not be established.”

This is also referred to in the other reference.

כִ֗י is used with …advs…. To add force or distinctness to the affirmation which follow:

Brown, Francis, 1849-1916. The Brown, Driver, Briggs Hebrew And English Lexicon : with an Appendix Containing the Biblical Aramaic : Coded with the Numbering System from Strong’s Exhaustive Concordance of the Bible. Peabody, Mass. :Hendrickson Publishers, 1996. p. 472

The meaning in Isaiah 7:9 is clear. It is not you believe not because you shall not established. Which is a causal meaning of כִ֗י but the meaning could be concessive which is an action that is accepted as true or conceded or making it impossible to rule out.

The Hebrew indicates a possible, and maybe better, translation of 1 Sam 2:25 as “Notwithstanding they hearkened not unto the voice of their father, therefore the LORD would slay them.”