Jamieson, Fausset and Brown on Romans 9:32-33

32-33. Wherefore? Because they sought it not by faith, but as it were--rather simply, "as"

by the works of the law--as if it were thus attainable, which justification is not: Since, therefore, it is attainable only by faith, they missed it.

for--it is doubtful if this particle was originally in the text.

they stumbled at that stumbling-stone--better, "against the stone of stumbling," meaning Christ. But in this they only did.