Answer:
One of the reason before why people worship idols is because at that time there was kind person who is a pious or a prophet at that time who tell to a nation about goodness and about God to worship god alone and to follow the law of god. after there died, people of the nation miss them so much until there make a idols of them so that there remember him and to remember of the good teaching about the law of god. by time to time after the new generation of the nation there don't know much about the idols that their father Glorify them so there start worshipping the idols for goodness like their father do before. After time by time their worship the idols and claim the idols is the god of them. This happen not in one nation but to a many nation before that have different language in a different places that each places god send for them a prophet with their language on this world before. And after time by time people change the teaching and the message of the prophet. Until god send the last final prophet for the hole humankind that is prophet Muhammad peace be upon him.
1) In islam have to believe that Jesus peace be upon him is a messenger of God and there are many messengers of God. example like moses and abraham and so on. We call them prophets ,some prophets have some power given by God. All prophets are human beings and there worship God and there bring the same message to humankind by the instruction of God to worship God the one and only and not to worship the stone or the idols or making partners with God. The Angel of Jibril is the angel that give the message to the prophet from God.
2) There are many prophets because when God send a prophet to humankind, by time through time people change the message and the teaching of the prophet until the religion is spoiled and there make partners with God and worship others then God again. That Is why God send another prophet to bring back the correct massage again for the humankind and that is why there are many religions that are wrong and worshipping wrong God .
3) prophet Muhammad is the last final messenger of God to bring back the message again and to stop the arabs land from worshipping the idols and the stone and making partners with God. Also for the hole humankind.
4) God the one and only have said in the Quran that only islam is the religion that is accepted in the side of God and islam means peace and submission to the will of God. And Muslim means the followers. And all Prophets are muslim. And God the one and only in arabic we call it (Allah). And islam is a religion of all Prophets from the beginning of humankind that is prophet adam to the last prophet that is prophet muhammad. Peace be upon them all.
5) so worship God the one and only (Allah) and do not worship the idols or the stone or the prophet or the jin or me or satan or the animals or the angel accept (Allah) the one and only.
6) And on this World is a test for humankind to seek and accept the truth and do righteous deeds or do not want and do bad. And only God the one and only (Allah) can give to his creatures the right path who wants it
