Albert Barnes Commentary Isaiah 41:21

"Produce your cause, saith Jehovah; bring forth your strong reasons, saith the King of Jacob." — Isaiah 41:21 (ASV)

Produce your cause - This address is made to the same persons who are referred to in (Isaiah 41:1)—the worshippers of idols. The prophet here returns to the subject, addressing a further argument on the comparative power of Yahweh and idols.

In the former part of the chapter, God had urged his claims to confidence based on several facts: he had raised up Cyrus; the idols were weak and feeble compared with him; and it was his fixed purpose to defend his people, and to meet and refresh them when faint and weary. In the verses that follow (Isaiah 41:21), he again urges his claims to confidence, this time from the fact that he alone was able to predict future events. He calls on the worshippers of idols to demonstrate their claims in the same manner.

This is the cause that is now to be tried.

Bring forth your strong reasons - Present the arguments that you consider to be of the greatest strength and power (compare the notes at Isaiah 41:1). The object is to call on them to bring forward the most convincing demonstration of their power and ability to save—the demonstration on which they relied.

The argument to which God appeals is that he had foretold future events. He calls on them to show that they had given, or could give, an equal demonstration of their divinity. Lowth regards this as a call on the idol-gods to come forth in person and show their strength. However, the interpretation that suggests it refers to their reasons, or arguments, aligns better with the parallelism and the connection.