Question: Could you tell me if what Amos 3:7 says about prophets applies today or not?
Response: The NIV's translation of Amos 3:7-8 goes as follows:
Surely the Sovereign Lord does nothing without revealing his plan to his servants the prophets. The lion has roared - who will not fear? The Sovereign Lord has spoken - who can but prophesy?
This comes in the wider context of verse 1-2 where Amos tells the people the Lord's words - that He has uniquely chosen them, and will therefore uniquely discipline them for their rebellious conduct as well.
The Lord's superintendence of the nation Israel, that is, His administration of (or dispensation of grace to) that special nation during the Jewish Age, always included the presence of prophets. Indeed, all the books of the Old Testament were penned under the authority and guidance of that divine gift. And there were, of course, many other prophets to whom it was given to prophesy (but not to have their messages included in the canon of scripture: e.g., 2Sam.24:11; 1Ki.1:8; 13:11; 1Chron.25:2-3; 2Chron.9:29), but who, none the less, pronounced the Lord's will and words to the Israelites.
Thus, the role of the prophet was primarily to make God's Word available to His people. And so it should come as no surprise that during the early Church, in the days before the Bible was finished (let alone readily available), there was a similar need for specially gifted individuals who would and could make God's words and will clear to new believers without recourse to the Bible we have today (1Cor.12:28-29; 14:29-32; Eph.4:11). It should also come as no shock that, as with other spiritual gifts that became unnecessary with the end of the Apostolic age and the establishment of completed canon of scripture (whose availability became widespread in short order), that this gift should also wane:
Love never dies. But if there are [gifts of] prophecy, they will be done away with. Or if there are [gifts of] tongues, they will stop [being given]. Or if there is a gift of knowledge, it will be done away with. For we know only partially, and prophesy only partially, but when what is complete has arrived [i.e., the Bible], what is partial will be done away with.
1st Corinthians 13:8-10
The notable absence of the gift of prophecy in the Church today is due to the fact that we have something even better, as Peter tells us: the Word of God itself in its completed form, our "light shining in the darkness" (2Pet.1:19). And let me follow Peter's lead and comment on the important caveat he records immediately following (2Pet.2:20): all true prophecy comes from God! That is to say, a person is not a prophet because he/she says so, but because God has given that person a gift and then further has given that person words to speak (Jer.1:9; 1Cor.12:11). It is very easy for someone to claim this sort of thing (compare Moses' words on the subject: Deut.18:17-22), but the actual occurrence of this gift has been very rare since the Age of the Church began (I personally am convinced that there has been no legitimate prophecy since the 1st Century). The issue and undue influence of false prophecy is destined to be a huge one as the Church enters the Tribulation: many will fall under the spell of some very convincing performers to their own grave spiritual damage (1Tim.4:1ff; 2Pet.2:1ff.; cf. Matt.24:11).
Finally, to return to Amos 3:7 in particular, it certainly was true that whenever God undertook to discipline His people Israel, He proclaimed this through His prophets (like Amos), so that Amos' remonstrance in this chapter is valid, true and worth paying attention to: when one hears the words of a prophet, one should take heed, because they often come when God is warning His people (in this instance as so often is the case, warning them to repent). Now there are no prophets today, as I have suggested above, but we do have the Bible, which is all prophecy, that is, the very words of the Lord God Almighty made available to anyone with the ears to hear. So in a much wider sense (to actually get to answering your question!), this verse does apply to us today, because God has given us something even better than a specific warning of some specific fault - He has given us all "the rules" in great detail, so that we are able to be completely informed about His manner and method of dealing with all people, individual and collective, eternal and temporal, and to be able to know these things with complete faith, for the veracity of this prophecy (the canon of scripture) is already well-established and accepted by all who are following Him and His Son Jesus Christ. Furthermore, we have, besides this general "template" of the Plan of God which the Bible contains, a very specific outline of the future history of the world, the very history of the Apocalypse, the events that will transpire all too shortly as this present age comes to an end. How marvelous, how amazing, to have history written before the fact, written by prophets from Moses to John, and recorded for us His children to know and appreciate ahead of time. This future history, as you know, is the focus of the series The Coming Tribulation: a History of the Apocalypse. For more on all this, please see the following links:
Spiritual Gifts and Spiritual Growth
The Gift of Tongues: Part 2
The Gift of Tongues: Part 1
Jesus is the Prophet
Prophets mentioned in the Bible
Is "the Prophet" of Deuteronomy 18:18 Muhammad?
The Old Prophet who Lied
The Lives of the Prophets
Yours in Christ,