The Two Testimonies
An informative lecture about understanding the two testimonies: There is none worthy of worship in truth except Allāh and Muḥammad is His Slave and Messenger.
The Messenger informed Muʿadh ibn Jabal, when he was going to the land of Yemen, "You are going to a people from the People of the Book, let the first thing that you call them to be the worship of Allāh. If they acknowledge this, then inform them that Allāh has obligated upon them five prayers during their days and nights. If they acknowledge this, then inform them that it is obligatory upon them to fast Ramaḍān. If they acknowledge this, then tell them that Zakāh is obligatory upon them (those who have more money than they need). If they acknowledge this, then tell them that going to ḥajj is obligatory upon them once in their life." [al-Bukhārī, Muslim]
Allāh created the human to worship Him, Allāh says (what can be translated as):
And I (Allāh) created not the jinns and humans except they should worship Me (Alone).
[Sūrah al-Dhāriyāt, 51:56]
From this (verse) we know the reason for being in this life. We were not created just to live and die. There is a hereafter that will be an eternal abode. Those who obey Allāh will enter Paradise and those who disobey Allāh will enter the Fire.