Peace, is of course, a synonym for contentment.
CAN be, not "is of course". Isaiah was speaking to a nation, not a person.
Phil 4:6-9 - Do not be anxious about anything, but in everything, by prayer and petition, with thanksgiving, gresent your requests to God. And the peace of God, which transcends all understanding, will guard your hearts and your minds in Christ Jesus. Whatever you have learned or received or heard from me, or seen in me - put it into practice. And the God of peace will be with you.
Word contentment not used.
Psalms 14:1 (again) - The fool says in his heart, "There is no God."
Says nothing about peace OR contentment.
Pslams 14:5 - There they are, overwhelmed with dread, for God is present in the company of the righteous.
Says God prodiuces dread, not contentment.
Psalms 29:11 - The LORD gives strength to his people; the LORD blesses *HIS* people with peace.
Says nothing about contentment.
Col 3:15 - Let the peace of Christs rule in your hearts, since as members of one body you were called to peace. And be thankful.
Says nothing about contentment.
If I was less lazy I could keep going. But knowing your response to these scriptures sort of takes the fun out of it.
My response? You were the one that said the scripture showed true contentment came from got and you have yet to show me a single scripture with that word.