I may be reading the question wrong. The way I see the question is it is addressed to those of us who believe there is only one God(swt) and we are being asked to give our understanding as to why we believe there is only one God(swt)
To begin with i will give my reason for knowing there is only one God(swt).
1. Only Allaah(swt) has revealed Himself to us throuh the Qur'an and the Prophets(PBUH) In the Qur'an Allaah(swt) has told us he has no partners or equals. For me that is sufficient to know there is only one God(swt)
Now from my human view point how do I understand there is only one God(swt). God(swt) by definition is omnipotent. If more then one God(swt) existed, he wold not be omnipotent as the powers would be shared. Also as stated in an earlier post if more than one God(swt) existed there would be a stuggle between them and chaos would reign without us ever being created. We were created so we know chaos does not reign, therefore there can only be one God(swt)
