How old was David?

From a message by a Curious Questioner--
>CQ> Subj: BOYS BECOME "MEN OF WAR"

>>>QC> See biblically, at age 12-13 boys became men.

>>RC> The biblical age when "children" become "men of war" is TWENTY. When the twelve spies returned from scouting the land of promise, and Israel refused to obey the LORD's command to enter the land, the LORD decided to eliminate all the "men" of that evil generation, except Joshua and Caleb.

"Moreover your little ones, which ye said should be a prey, and your children, which in that day had no knowledge between good and evil, they shall go in thither, and unto them will I give it, and they shall possess it." (Deut.1:39)

>>RC> The age of the "men" was "twenty years old and upward", so their little ones and children were therefore less than twenty years old. (In plainer words, Teenagers are "children"! :)

>CQ> Without seeming foolish, let me ask one question:
How old was David when he slew Goliath?

David slew Goliath in 1Sam.17:50,51. David was already "anointed" to be king back in 1Sam.16:14, and he was called, "a mighty valiant man, and a man of war..." in 1Sam.16:18p.

Ussher's chronology is interpreted as having David born in bc1090, dying in bc1015, and slaying Goliath in bc1063 which would make him 27 years old when Goliath fell, and David's death at 75 years old. However, that would have David beginning his 40 year reign as king after Saul's death, in bc1055, and the end of his reign in bc1015, which would make him 35 years old beginning his reign.

"David was thirty years old when he began to reign, and he reigned forty years." (2Sam.5:4) (the only place where we are told outright how old David was. :)

So, obviously the standard interpretation of Ussher's chronology seems to be off by 5 years concerning the birth year. That bc1090 date was beside 1Chron.2:15, which says, "Ozem the sixth, David the seventh:" So, that date can only apply to Ozem, not to David, who would have to have been born 1055 + 30 = bc1085. (1085-1063 = 22 :)

So David would have been at least 22+ years old when Goliath fell.

The grace of the Lord Jesus Christ be unto you. Amen. --Richard