Different Religion Different gods?

Everyone claim that their religion is religion and their god is god . They refuse other gods and religions prevalent in the world. They identify themselves with either Hindu or Christian or Muslim or Other. Some of them even make quarrel in the name of religion. It is one of the serious problem of the world now. More than problem it is the fundamental misunderstanding of the civilization.
Actually, the above mentioned identification are the categories of faith in God. Religion is one for all and God is one as per the definition of those words. Religion is defined  from time immemorial as the eternal occupational duty of loving the Supreme being by the individual souls and Supreme being  called God. By definition there can not be two or more than two supreme beings at a time. So, it is also self evident that there is only one God. Then why are there many religions and many god? The question is not only sensible but weighty as well.
First of all let us take the example of treatment system for a disease. The same disease can be treated in multiple ways such as there is allopath, there is ayurveda, there is homeopathy, there is naturopathy. And even further, within allopath there might be clinical treatment, there might be surgical treatment, there might be counseling as a psychological treatment which primarily involves discussion not medication. So all these different medical practices or systems have ultimately one person to cure, one purpose that is to cure the patient. Similarly, there are different process in the world to take us near God, back home to Godhead. In the world there are different categories of people who can adopt religious lifestyle in different nature and degree. Thus there should be different religions in the world. But, ultimately all religions have the common goal and hence common God. This should be understood.