...And whosoever disbelieves in the Oneness of Allâh and in all the other Articles of Faith [i.e. His (Allâh's), Angels, His Holy Books, His Messengers, the Day of Resurrection and AlQadar (Divine Preordainments)], then fruitless is his work, and in the Hereafter he will be among the losers.(5:5)
The verse (5:5) is talking about the oneness of Allah (SWT), which is the most important. But the oneness also has details, in order to depend fully on Allah (SWT) in terms of financial, or any matters which may be good or bad, and this is all from Allah, the only one source, which keeps managing work, and that source is Allah.
The main and the most important pillars, which faith is based on is to believe in Allah, his angels, his books, and the day of judgment, and divine preordainments (Al-Qadar), which means matters that are good and bad are from Allah, this means that Allah has angels who manage all of our worldly matters, and anything because of our action is made to be bad, and we are the one's who follow it, after Satan shows us so many attractions, and we are the one's who go in trouble, and it is Allah, who removes the trouble away from us, and life after death.
Whenever we do any good deeds in this world, up to any extent is useless if we are missing a single pillar of iman, to understand. It is advised to remind oneselves of these pillars, after fajr (dawn prayer), and Isha (evening prayer).
...And he who changes Faith for disbelief, verily, he has gone astray from the right way. (2:108)
(2:108) What are we being told to by Allah. All of us think we are Muslim, how are we leaving iman (belief)? our forefathers were Muslim But we can see in today's busy life, our prayers are left behind, and we are only busy day and night in matters related to this world, if Allah has even made us an owner of this world, we will still have never ending wishes and desires.
We always think that if we have a cycle, then we dream for a motorcycle, and if we have a motorcycle, then if we have that then we want a car, ect. One's needs can never be fully satisfied. And this habit has made us more and more unthankful for the bounties provided by Allah (SWT), and this is how disbelief is being brought. And this is taking us far away from the straight path.