Before Islam, there were some major beliefs which shaped the ideology of the early Arabian society and which the prophet Muhammad (BBUH) declared inappropriate:
1. People are born of certain qualities, slaves, non-slaves, workers, masters:
The Arabian society was based on classification according to a number of social ranks. This classification was accompanied by certain rights and duties for different classes of the community. Islam called for abandoning the core belief that people are born different. Islam stated that there is no advantage of someone over another except the devoutness to God which is determined only by God not by humans.
That way, Islam did not only denounce aristocratic privilege, reject hierarchy, and adopt a formula of career open to the talented but also built stronger social bonds among different social groups. These bonds were the direct result of not alienating minorities and other social groups by not giving them fair rights and duties given to the rest of the society. Islam also established rules for a Muslim who wants to become a better person, stronger devoutness to the God and better implementation of Gods orders.
2. The poor has right in the rich money:
A further improvement of the Arabian society was established by confirming the fact that a certain amount of money must be paid by rich people to the poor ones. This doctrine of zakat, or alms for the poor, was important in the development of a tightly knit community of believers - and, ultimately, of Islam's success.
3. Rejection of the faith of pagans and their inappropriate practices:
The prophet (pbuh) logically rejected the idea of a statue being the God of mankind even before the angel Gabriel delivered the instructions of God to him.
The first instruction was that only one god existed, and that strict monotheistic belief was required of all people. The first thing for anyone to be a Muslim is to declare faithfully that there is no god but Allah.
4. Existence of final judgment day:
The concept of a final judgment day was absolutely absent in early Arabs' minds. This concept was then announced by the prophet Muhammad (pbuh). The concept spread a sense of responsibility for one's deeds and the importance of doing good deeds in preparation for this day.
5. The community is a whole however diverse it maybe:
Before Islam, the Arab community was divided into tribes of common ancestors and interests. However, Islam came to appreciate the unity of the society to become one Ummah (community).