Move on. There is nothing to be gained from arguing with the editor who rejected your manuscript. Rejection is a fact of life in academia. It's disappointing but it's the price we pay to be able to maintain high academic standards. One rejection is not the end of the research. I've had papers rejected three or four times before being accepted, and then when published have gone on to be well cited. The positive side of a rejection decision is that you now have some independent feedback on your work. Try to accept that feedback, revise your manuscript, and submit elsewhere. If you persevere you can get it published somewhere else.