Often times God would call a prophet who had trouble speaking and was very frightened of speaking publicly.
Moses stuttered and begged God put someone ahead of him to do the speaking.
Jonah was afraid to go to Nineveh, fearing the people would not hear him.
Jeremiah said, "I am only a child" not confident that he could confront the nation and speak stern words against it.
Isaiah entered into the presence of God and said, "Woe unto me! I am ruined! For I am a man of unclean lips."
What was different in the New Testament was the apostles who were very gifted and persuasive speakers, but of course, they had the greatest Teacher who they lived with, ate and slept with for over three years.
But the prophets of old were incredibly awkward. Elisha was mocked for being a 'bald head'. Isaiah went naked for 430 days. Ezekiel ate a.. something, you can read that one later. Amos was a simple countryman, a herdsmen, probably not what the enlightened cosmopolitan culture would think of as progressive. None of the prophets were 'ideal' in any true sense of the word.
Which is all the more the challenge for us when we see young, backwards, simple folk who speak in biblical proportions or with a similar conviction. The Judeans thought of the countryfolk, the unlearned in the synagogues, the outcasts like we do today.
It sounds to me like you are trying to say that men today who speak with "similar conviction" can be compared to the prophets of yesterday, even though they are "backwards," because so were the prophets in their day. Am I right? Is that the argument you are trying to build?
If so, then you need to understand that there is a HUGE difference between the prophets of old and the men (and women) who speak "a word for the Lord" today: The prophets were ACTUALLY GIVEN their words by God! They were ORDERED to speak on YHWH'S behalf! And, if they refused to do so, that's when the things about which they were to warn the people happened to THEM instead! (Or, at least, that's what they SAID would happen to them, and feared that God would do to them!) Their drive to speak for the YHWH came FROM YHWH; it was NOT just a "conviction." It was a COMPELLING! It was a COMPULSION! It was COMPULSORY!
9 Then I said, I will not make mention of him, nor speak any more in his name. But his word was in mine heart as a burning fire shut up in my bones, and I was weary with forbearing, and I could not stay.
Consider also the compulsion placed on the first king of Isra'el, Sha'uwl (Saul):
1 Samuel 10:1-13
1 Then Samuel took a flask of oil and poured it on Saul's head and kissed him, saying, "Has not the Lord anointed you leader over his inheritance? 2 When you leave me today, you will meet two men near Rachel's tomb, at Zelzah on the border of Benjamin. They will say to you, 'The donkeys you set out to look for have been found. And now your father has stopped thinking about them and is worried about you. He is asking, "What shall I do about my son?"'
3 "Then you will go on from there until you reach the great tree of Tabor. Three men going up to God at Bethel will meet you there. One will be carrying three young goats, another three loaves of bread, and another a skin of wine. 4 They will greet you and offer you two loaves of bread, which you will accept from them.
5 "After that you will go to Gibeah of God, where there is a Philistine outpost. As you approach the town, you will meet a procession of prophets coming down from the high place with lyres, tambourines, flutes and harps being played before them, and they will be prophesying. 6 The Spirit of the Lord will come upon you in power, and you will prophesy with them; and you will be changed into a different person. 7 Once these signs are fulfilled, do whatever your hand finds to do, for God is with you.
8 "Go down ahead of me to Gilgal. I will surely come down to you to sacrifice burnt offerings and fellowship offerings, but you must wait seven days until I come to you and tell you what you are to do."
9 As Saul turned to leave Samuel, God changed Saul's heart, and all these signs were fulfilled that day. 10 When they arrived at Gibeah, a procession of prophets met him; the Spirit of God came upon him in power, and he joined in their prophesying. 11 When all those who had formerly known him saw him prophesying with the prophets, they asked each other, "What is this that has happened to the son of Kish? Is Saul also among the prophets?"
12 A man who lived there answered, "And who is their father?" So it became a saying: "Is Saul also among the prophets?" 13 After Saul stopped prophesying, he went to the high place.
(I used the NIV simply to save space and make it more understandable.)
It's not about the "conviction" of the person; it's about the "COMPULSION" of YHWH! It wasn't at the whim of the speaker; it was at the ORDER of YAH! Whether they wanted to say something or not, they were COMPELLED to say His Word! If they tried to resist, His Word would BURN within them!