Part of the ongoing Verse Quick Reference project.
Isa 55:8 “For My thoughts are not your thoughts, Nor are your ways My ways,” says the LORD.
Isaiah 55:8 is often used by those wishing to justify what they claim are God’s acts. Something tragic will happen. God will be said to have done this. And then if they are questioned about this, they will claim that “God’s ways are not our ways.” This is to say that God has some mysterious plan that He is working. But the context of Isaiah 55:8 point to an entirely different meanings:
Isa 55:7 let the wicked forsake his way, and the unrighteous man his thoughts; let him return to the LORD, that he may have compassion on him, and to our God, for he will abundantly pardon.
Isa 55:8 For my thoughts are not your thoughts, neither are your ways my ways, declares the LORD.
The context is about God’s repentance. If the wicked repent, God will pardon. In this way, God’s thoughts are not our thoughts and God’s ways are not our ways. While man might not pardon someone who has wronged them, God is open to forgiveness.
The point of Isaiah 55:8 is not that God has some secretive plan that no one can understand, but that God is less vindictive than man. The text is expressly about God telling us how He operates, so it is not some secret surprise. The text is one for clarity, not confusion.
God is Open 
I most often hear this verse as a cop out when people can’t explain how one part of their theology is paradoxically opposed or even flat-out contradicts another part. What’s frustrating is they usually do so while changing their exposition of a passage to fit their theology. So they misconstrue a text to fit their platonic theology, then use a verse out of context to justify doing so. It’s like a double dip.