Jesus was very clearly saying that all this activity in the temple, the effective exclusion of gentile believers from worship, the way in which very real barriers had been put up to stop sections of the community worshiping was robing God of his glory – and so Jesus overturned the tables and cleared the temple.
James is encouraging us to give ourselves completely to God because the thing that God desires from us above all else is that we would be exclusively his. Or do you think Scripture says without reason that he jealously longs for the Spirit he has caused to dwell in us. (James 4:5) God looks at us like a jealous lover. He has invested everything in us, he made us in his own image. Nothing else in creation has that honour, he gave his Son for us, he promises his Spirit will dwell in us, he was the one who breathed life into us and so God is jealous for us and yet we live life in two camps, not fully committed to either and this is the reason we are powerless and flat.