Since I Corinthians 14:7 mentions instruments, doesn’t that justify instrumental music in the worship?

Answer:

"Follow after love, and earnestly desire spiritual gifts, but especially that you may prophesy. For he who speaks in another language speaks not to men, but to God; for no one understands; but in the Spirit he speaks mysteries. But he who prophesies speaks to men for their edification, exhortation, and consolation. He who speaks in another language edifies himself, but he who prophesies edifies the assembly. Now I desire to have you all speak with other languages, but rather that you would prophesy. For he is greater who prophesies than he who speaks with other languages, unless he interprets, that the assembly may be built up.

But now, brothers, if I come to you speaking with other languages, what would I profit you, unless I speak to you either by way of revelation, or of knowledge, or of prophesying, or of teaching? Even things without life, giving a voice, whether pipe or harp, if they didn't give a distinction in the sounds, how would it be known what is piped or harped? For if the trumpet gave an uncertain sound, who would prepare himself for war? So also you, unless you uttered by the tongue words easy to understand, how would it be known what is spoken? For you would be speaking into the air" (I Corinthians 14:1-9).

When dealing with a quote from the Scriptures the context must always be considered. I Corinthians 14:7 falls in a section where Paul explains that speaking in other languages (speaking in tongues) is of limited use. It appears to have been popular in the Corinthian church because it was a showy gift, but Paul points out that there are two major limitations to the gift. First, the gift is useless if someone doesn't understand what is being said. Second, the gift is worthless if something meaningful isn't said. The verse you quote falls in the second argument and serves as an illustration to the point. Why would someone want to listen to a flute being played if there was no tune? Or what use would a bugle call be if the sound didn't carry a message, such as "advance?"

The worship service is not being discussed at this point. Nor is the illustration one from a worship service. To apply an illustration beyond the intention of the context is to do injustice to the Scriptures. It would be taking it out of context. If verse 7 would justify instruments in worship, then verse 8 would justify keeping a platoon of soldiers in the church building.