Job summarises what he has learnt from the Lord’s illustrations: God can do anything he wills and no power can stand in his way, no unforeseen obstacle can arise to frustrate him: what he wills is as good as done..
From these firm rebukes of the Lord Job now says, ‘I know…’., but before he did not see God could do anything. He cried out, ‘Why doesn’t God deal with the wicked?’ Now he is ashamed of that sort of complaint. ‘Terrible things have befallen me, but I know the Lord is in control.’ He affirms what he can be certain of. It is good sometimes to see our lives in this way – to affirm the discoveries we make from God: ‘O Lord, I know this is true, that is true.’ When we see things like this, God does turn us. We must absolutely trust.
Some versions render this along these lines: ‘I know no purpose of yours can be thwarted’, but the KJV understands the purposes or thoughts to be those of men, not of God, and so understand it to mean that nothing can be hidden from the Lord. That would mean not that God knows every thought, and therefore we had better watch out, but that God knows your case, he knows your fears, troubles, what you are going through.
Calvin understands it to refer to God purposes and comments, ‘Many fanatical persons, when they talk of God’s almightiness, say, “If God is almighty why does he not do this, and if he is almighty he can do that. Yes, but we must not allow our imaginations to carry us away. God’s almightiness does not concern any common thing. God’s almightiness and his will are two inseparable things. God is almighty, but is it to do what man invents in his brain? No, but it is to accomplish whatsoever he has ordained in his own purpose … The things to which we should apply God’s almightiness is that he will keep his promise, and that because our welfare is in his hand we are sure that no evil can befall us’ (Calvin in modern English).