We are plagued on all sides by deception and false prophets. However, it doesn't mean the gifts of the Spirit, such as prophecy have ceased. We are to judge such words:
1 Co 14:29 Let the prophets speak two or three, and let the other judge.
But let's not throw the baby out with the bath water:
1 Th 5:20-21
Despise not prophesyings. Prove all things; hold fast that which is good.
Those verses prove that prophecy was taking place when Paul wrote to the Thessalonian and Corinthian churches. They do not prove that Christians after the apostolic age would continue receiving
new revelations from God.
First Thessalonians 5:19–22 says: “Quench not the Spirit. Despise not prophesyings. Prove all things; hold fast that which is good. Abstain from all appearance of evil.”
Paul was telling them not to reject every prophecy automatically, but he was also telling them not to believe every claim.
They were to test everything.
That agrees with 1 Corinthians 14:29: “Let the prophets speak two or three, and let the other judge.”
And 1 John 4:1 says: “Beloved, believe not every spirit, but try the spirits whether they are of God.”
But none of those verses says that Christians after the apostles would continue receiving new revelations from God. They explain how prophecy was to be judged
while prophecy was still operating. They do not say it would continue throughout the entire church age.
The question is not whether prophecy existed.
Of course it did. The question is where the Bible says God would continue giving new prophetic messages after the apostolic foundation had been laid.
Ephesians 2:20 says the church was “built upon the foundation of the apostles and prophets.” A foundation is laid once. Jude 3 says the faith was “once delivered unto the saints.” Second Timothy 3:16–17 says Scripture thoroughly furnishes the man of God unto all good works.
I am not throwing the baby out with the bathwater. I like to know where it says Christians after the apostolic age would continue receiving new words from God so they can add to God's word? Quoting instructions given to churches while apostles and prophets were still present does not prove that.
First Thessalonians 5:20–21 cannot just be quoted as proof of modern prophecy. It says prophecy was not to be despised and every claim had to be tested. It does not say people centuries later would continue receiving new revelations from God.
Today, every claim must be tested by the written Word of God. If it adds to Scripture, changes Scripture, contradicts Scripture, or claims authority equal to Scripture, it must be rejected.
Preach the Word God has already given. Do not claim that God gave you a new message unless you can prove from Scripture that He promised to continue doing that after the apostolic age. Proverbs 30:6 gives a serious warning:
“Add thou not unto his words, lest he reprove thee, and thou be found a liar.”
This is not a salvation issue unless supposed prophecy changes the gospel, adds another way of salvation, denies Christ, or is treated as equal to or above Scripture.