What does the suffix -eth mean?

My fear is that even the dictionary's don't have the direct usage perfect.
What I could pick up from the definition below is the word "Present"... the "ETH" implies a continued present action, not past or not future, but NOW!...

ie.... He that "BELIEVETH" and is baptized shall be saved. Mark 16:16 kjv

that is not "Once" believed, or Will Believe, but Presently believing. I believe "S" is not strong enough ie. Believe(s) The TH is like an exclamation mark. "!"

Definition of -ETH
Used to form the archaic third person singular present of verbs <doth>
This is one of the reason's I like the King James Version. It preserved the usage to be most accurate to the originals.

Why Do We Need "Thee" and "Thou"?
Issue Date: May/June 2000

In almost every language but Modern English, people knew whether the speaker was addressing one person or many. In Classical English, this is preserved. If the speaker is talking to one person, he uses "thee" or "thou." If he is talking to many people, he says "you" or "your." The King James preserves this distinction.
When Jesus spoke to Nicodemus, He said, "Marvel not that I said unto thee, ye must be born again" (John 3:7). What He said in effect was, "Marvel not that I said unto thee (Nicodemus), ye (all of you people) must be born again." Jesus did not tell this only to Nicodemus.
He spoke to all people of all times, from those who stood around that night, even to us today: Ye must be born again!
From The King James Bible Companion by David W. Daniels.