Question: How is Isaiah 38:1-5 not either God lying or God changing His mind?
Answer: Here is the passage:
In those days Hezekiah became sick and was at the point of death. And Isaiah the prophet the son of Amoz came to him, and said to him, “Thus says the LORD: Set your house in order, for you shall die, you shall not recover.” Then Hezekiah turned his face to the wall and prayed to the LORD, and said, “Please, O LORD, remember how I have walked before you in faithfulness and with a whole heart, and have done what is good in your sight.” And Hezekiah wept bitterly. Then the word of the LORD came to Isaiah: “Go and say to Hezekiah, Thus says the LORD, the God of David your father: I have heard your prayer; I have seen your tears. Behold, I will add fifteen years to your life.
In a sense that is like asking, “Why pray, we can’t change God’s mind? ” There is no doubt some mystery as to how prayer works. I would argue that God does sovereignly determine the course of life’s events but knows in His plan that we will pray and plans on answering those prayers. But what about this particular incident with Hezekiah?
We see the same pattern with Hezekiah as we do with Jonah, when God tells the people of Nineveh through Jonah that in three days they will be destroyed but he only tells them that so they can have a chance to repent. He only sends Isaiah to tell Hezekiah he is going to die so that Hezekiah has a chance to pray for another option. And then God rewards prayer with an answer.
As with much prophecy in Scripture that is negative in scope, there is this implied opportunity to change the outcome if Hezekiah responds, just as there was an implied opportunity for the people of Nineveh to respond and change the outcome. We are not used to these kind of prophetic situations so we don’t understand the implications. If Hezekiah doesn’t respond the way he did he does die as God foretold. God’s communication is not intended as unalterable. Hence, no lie or changing of mind.
Interestingly, we learn that Hezekiah had to go have a poultice applied to his wounds in order to be healed. A supernatural healing through natural means.
Ask the Pastors 
My understanding is God given Hezekiah a chance to repent. Just of this world today people think they are living righteously but are not.
I agree that Gods intention or action(sending the prohet) is absolutely good,however the fact remains that the actuall delivered message did change,so does the means justify the method?
Sometimes the end does justify the means. But in this case it isn’t true, I don’t think, that God is simply telling Hezekiah he is going to die in order to get Hezekiah to ask for more life. He is simply giving him a choice. He could have accepted this from God’s hand and been content to finish out his life then, or he could ask, as he did, for an extension.