There are continuous frictions between belief (Iman) and disbelief (Kufr) which everyone experiences, and will experience, until the world will become unsustainable to exist. Every human alive are always in a state of either belief or disbelief. Those experiences or states people find themselves in can be in change from time to time, inwardly and outwardly.
This two polarised beliefs has always existed from the beginning of man as cited clearly in the Qur’an. Some Prophets of Allah were killed for delivering the message of Tawhid (Oneness of Allah).
So, for the ones in belief, there will always be disbelief as an opposition, as obviously belief is the opposite of disbelief. The power of belief is better than the power of disbelief, and as we know that there is no power and might except by Allah.
Humans were all created weak, and knowing full well we could be susceptible to the disbelieving force that exists in luring us all. But, Allah is All- Relenting (At – Tawwab) and wants everyone to turn back towards Him, in submission.
Everyone have been and is going to be affected, accordingly to the nature and setting created by Allah, may it be positively or negatively. As we know Allah started and is the sole originator of creation.
So we are told in the Qur’an how Islam completely fits the way, the whole nature and setting of how creation has been made from the beginning by Allah.
Everything happens by Allah and all matters return to Allah.