The word "confidence" can be expressed with the adjective "confident." The word "terror" can be expressed with the adjective "terrified." Alternate translation: "They will no longer be confident because they are so terrified" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])
Both of these clauses mean the same thing and are used together for emphasis. Here God's presence and his power to judge and destroy are spoken of as if they were a fire. Alternate translation: "whose powerful presence is in Zion" (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-metaphor]])