Allah had sent all his messengers since Noah till Muhammad (Peace be upon them) to tell people his instructions and commands ,and also, to warn them his punishment. But those messengers were faced with rejection and mockery. Nevertheless ,Allah has established the argument and evidence upon those folks. On the other hand,Allah has told those folks if they did not obey him and listen to his messengers ,he will followed them with loss and regret in their hearts.As he said in the holy Qur’an {Alas for mankind! There never came a Messenger to them but they used to mock at him.}Abdullah Bin Abbas
May Allah be pleased with him said[Alas for mankind! ]that is woe upon those slaves.narrated Abo Hrairah :The prophet [pbuh] said:{All the people of Hell see their seats of Paradise then everyone says if Allah guided me ,then it will be loss and regret on him , and the prophet said:All of people in paradise ,everyone of them sees his seat of Hell and then says if not Allah guided me ,the prophet said and that will be thanksgiving for him}musnad Al-Imam Ahmad. 2/512
It is a mercy of Allah that he sent the messengers to salvage folks from ruin in life and after death.Allah does not want to torment his slaves but he wants them to thank him and be on the straight path which he had mentioned in the holy Qur’an and in his messengers messages .Allah said ;
{Why should Allâh punish you if you have thanked (Him) and have believed in Him. And Allâh is Ever All-Appreciative (of good), All-Knowing. }4/147.
One of the most important in the messengers invitations is that they all invite to monotheism which is the base of Islam as Allah said in the holy Qur’an:
{And to ‘Âd (people We sent) their brother Hûd. He said, “O my people! Worship Allâh! You have no other ilâh (god) but Him. Certainly, you do nothing but invent lies! }11/50. By this kind of monotheism Allah will not accept any deed without it,this is what we call Unity of worship ,namely to believe that non has the right to be worshipped but Allah.This type of monotheism is that for which Allah sent messengers and revealed books.
