We are pleased to consider your question: how can one know with certainty who is and who is not a messenger from God. In other words, you want to know how you may know a false teacher. This is easy enough if our heart is right before God, and we are convinced that the scriptures are in fact the very word of the living God.
The beginning of another gospel began in the garden, where the arch-enemy whispered: ‘hath God said?’ thus the legacy of doubting God’s word has survived rather well.
The devil tried more of the same with the last Adam, the Lord Jesus, but the Lord would have none of his mischievous handling of the word of God. And herein lies the seed of unbelief, despair, and doubt, as we see how Satan handles the word of God.
He recognizes it, even quotes it, but it is his misrepresentation and half-truths which are the most egregious of all. So it is no wonder that men do the same, thus the results are easy to notice, as all false teaching casts doubt on the very word of God.
We are reminded that in our day, seducing spirits bring damnable heresies because there is always a market for unbelief, as man always has itching ears. Paul said that from among the ranks of christendom would men arise, who would speak perverse things with the sole desire to make likenesses of themselves.
The erosion of truth is the fruit of false teachers whose message is antagonistic to the grace of God. Paul also said through the spirit of God that they speak lies through hypocrisy, while we read in another place these men foam out their own shame. Yuck.
The word of God tells us you can tell a tree by the fruit, and a dead giveaway of sad teaching is the obvious rotten fruit, for out of the abundance of the heart the mouth speaketh.
We are told to be wary of any who brings another message than that which Paul called my gospel, as the apostle proclaimed a divine anathema on all who would pervert the gospel of Christ. See what message he preached in Acts 13, and see if the men you listen to bring this gospel, for this is exactly what Paul had in mind in Galatians 1, for he is speaking of Antioch Pisidia, in Galatia.
The apostle, evangelist, pastor, and teacher Paul, wrote as a prosecuting attorney in the book of Romans. This man of God stated with heavens blessing that by the works of law, that is, any law, shall no flesh be justified in the sight of God. Every mouth is stopped, and the whole world is guilty before God.
The indictment has been handed down, and man is totally contemptible. But the apostle argues now for the defense, and presents the righteousness of God as demonstrated in the gospel of Christ as mans only hope.
The apostle concludes the heart of the matter in Romans 3. And what is a conclusion but the end of all question, thus any message that does not agree with Paul’s as to how a sinner is made right before God, is simply false.
So while we can not tell you who a man of God is nowadays, it should be apparent who is not. You may have heard it said that Adam was not the first man created by God. Clearly, Paul said he was, as well as David, Job, the Lord Jesus, and the entire warp and woof of scripture proves this.
Now then, may you draw your own conclusions? You may have heard it said that Ireland, Germany, Japan, or the United States is the new and improved promised land. Where do you suppose this teaching comes from, for he who said the word of God contains ALL that pertains to life and godliness, knew nothing of this diabolical waste of good words.
So we are told, by good words and fair speeches they deceive the hearts of the simple. If you are indwelt by the Holy Spirit of the living God, he can help you know who is false, for he points you to he alone who is true. Sha alu shalom Yerushalim.