Allaah has sent all of the Messengers [(عليهما الصلاة والسلام) (‘alaihim us salaatu was salaam) Upon them prayer and peace] as bearers of good news, warners, leaders, and those who guides to that which is right. 

Allaah the Most High says,

رُسُلا مُبَشِّرِينَ وَمُنْذِرِينَ لِئَلا يَكُونَ لِلنَّاسِ عَلَى اللَّهِ حُجَّةٌ بَعْدَ الرُّسُلِ وَكَانَ اللَّهُ عَزِيزًا حَكِيمًا

[Messengers as bearers of good news as well as of warning In order that mankind should have no plea against Allaah after the Messengers. and Allaah is ever All­Powerful, All­Wise.] سورة النساء – Soorah an-Nis’aa [4:165]

All of the Messengers (عليهما الصلاة والسلام) called their people to believe properly in Allaah, make all worship sincerely to Allaah alone as well as to disbelieve in all that is worshipped other than Allaah. This was the call of all of the Messengers (عليهما الصلاة والسلام).

Allaah the Most High says,

وَلَقَدْ بَعَثْنَا فِي كُلِّ أُمَّةٍ رَسُولا أَنِ اعْبُدُوا اللَّهَ وَاجْتَنِبُوا الطَّاغُوتَ فَمِنْهُمْ مَنْ هَدَى اللَّهُ وَمِنْهُمْ مَنْ حَقَّتْ عَلَيْهِ الضَّلالَةُ فَسِيرُوا فِي الأرْضِ فَانْظُرُوا كَيْفَ كَانَ عَاقِبَةُ الْمُكَذِّبِينَ

[And Verily, we have sent among Every Ummah (community, nation) a Messenger (proclaiming): “Worship Allaah (Alone), and avoid (or keep away from) Taaghoot (all false deities, etc. i.e. do not Worship Taaghoot besides Allaah).” Then of them were some whom Allaah guided and of them were some upon whom the straying was justified. So travel through the land and see what was the end of those who denied (the truth).] سورة النحل – Soorah an-Nahl [16:36]

قُولُوا آمَنَّا بِاللَّهِ وَمَا أُنْزِلَ إِلَيْنَا وَمَا أُنْزِلَ إِلَى إِبْرَاهِيمَ وَإِسْمَاعِيلَ وَإِسْحَاقَ وَيَعْقُوبَ وَالأسْبَاطِ وَمَا أُوتِيَ مُوسَى وَعِيسَى وَمَا أُوتِيَ النَّبِيُّونَ مِنْ رَبِّهِمْ لا نُفَرِّقُ بَيْنَ أَحَدٍ مِنْهُمْ وَنَحْنُ لَهُ مُسْلِمُونَ

[Say (O Muslims), “We believe In Allaah and that which has been sent down to us and that which has been sent down to Ibraaheem (Abraham), Ismaa’eel (Ishmael), Ishaaq (Isaac), Ya’qoob (Jacob), and to Al-Asbaat [the twelve sons of Ya’qoob (Jacob)], and that which has been given to Moosa (Moses) and ‘Isaa (Jesus), and that which has been given to the Prophets from their Lord. We make no distinction between any of them, and to Him we have submitted (in Islaam).”] سورة البقرة – Soorah al-Baqarah [2:136]

The first Messenger was Nooh [(عليه السلام) (alaihis-salaam) Peace be upon him]. Allaah sent Nooh (عليه السلام) to his people in order to call them to the worship Allaah alone and to leave off the worship of the idols.  His people went against him and did not obey him.

The  Messengers continued and followed in secession after Nooh (عليه السلام) until Allaah sent  our Prophet, The last Prophet and Messenger, Muhammad [(صلى الله عليه وسلم) (sallallaahu ‘alayhi wa sallam) May the peace and blessings of Allaah the Most High be upon him]. His message is the sum of all previous messages, (as the religion of the Messengers is one). Islaam is the foundation for true life, that which will rectify the (problems of humanity), and the completion of Allaah’s favour upon mankind. The message was thus completed with our Prophet Muhammad (صلى الله عليه وسلم).