The passage of 2 Kings 20:1-20 explains how king Hezekiah was warned by God through prophet Isaiah that he would die soon. The king then reminds God of his behaviour in front of Him and he weeps bitterly. After this, God ordered the prophet to return to king Hezekiah and tell him that God added 15 years to his life.
Anti-Open Theist Bruce Ware wrote on this passage:
"Does it not seem a bit odd that this favorite text of open theists, which purportedly demonstrates that God does not know the future and so changes his mind when Hezekiah prays, also shows that God knows precisely and exactly how much longer Hezekiah will live? On openness grounds, how could God know this? Over a fifteen-year span, the contingencies are staggering! The number of future freewill choices, made by Hezekiah and by innumerable others, that relate to Hezekiah's life and well-being, none of which God knows (in the openness view), is enormous." - Bruce A. Ware, God's Lesser Glory: The Diminished God of Open Theism (2000), 95-96.
Here is my problem with Bruce Ware’s take on Open Theism and on this text in particular: He blames Open Theists for representing a diminished God. But whose representation of God is really diminished? Ware represents the God of the Open Theists (the Christian God) as unable to make sure exactly 15 years are added to Hezekiah’s life. I have not heard a single Open Theist deny the possibility of this choice within God’s range of sovereign choices.
As Job put it:
"When I was born into this world, I was naked and had nothing. When I die and leave this world, I will be naked and have nothing. The Lord gives, and the Lord takes away. Praise the name of the Lord!" - Job 1:21 (ERV)
ps. Here you have the image of a seal of king Hezekiah depicting the ank (cross-like symbol which is a symbol of life). Did he add this symbol to his seal as a way of reminding himself of the great grace God had shown to him?:
picture source: christianpost.