As those who don't belive in Allah due to any reason. Thus does Allah sustain and provide them as they deny his existence ?
Allah's رحمة (mercy\compassion) extends to everything.
ورحمتي وسعت كل شيء
My mercy encompasses all things
ربنا وسعت كل شيء رحمة
Our Lord, You have encompassed all things in mercy
And it should be obvious that He does sustain and provide for disbelievers as well as believers.
His محبة (love) does not extend to everyone, for example:
فإن الله لا يحب الكافرين
Allah does not love the disbelievers
والله لا يحب الظالمين
Allah does not like the unjust
إنه لا يحب المستكبرين
He does not like the arrogant
إنه لا يحب المسرفين
He does not like the extravagant
والله لا يحب المفسدين
Allah does not like the mischief-makers
إن الله لا يحب كل خوان كفور
Allah likes not any treacherous ingrate
يأتي الله بقوم يحبهم ويحبونه أذلة على المؤمنين أعزة على الكافرين يجاهدون في سبيل الله ولا يخافون لومة لائم
Allah will bring a people whom He loves and who love Him, humble toward the believers, hard on the disbelievers, who fight in the way of Allah and are not afraid of the reproach of any critic.
Verse 2/126: And when Ibrahim sail: my Lord, make this city (Mecca) a secure land and provide its people with fruits, those who believe in Allah and the Last Day, He (Allah) said: And those who disbelieve, I shall leave him to enjoy a while, then I shall compel him to the punishment of the Fire, as evil destination.
Means they will be left till the last breath to believe and enjoy this world, if not then they will be resting in hell fire.
Compare to Aakherat this life is very short.
"O mankind, remember the favor of Allah upon you. Is there any creator other than Allah who provides for you from the heaven and earth? There is no deity except Him, so how are you deluded? “ (35 : 3)
It must be noted that the above verse does not address Muslims exclusively, but begins with the inclusive address “O humankind” to embrace all humanity. It reminds humanity that they belong to one family. Same message gives the below mentioned hadith that all creation are like a Allah’s family.
The Messenger of Allah has said: “All creatures are Allah’s family; and Allah loves most those who treat his family well and kindly”. (Bayhaqi)
Allah is the universal Creator, Sustainer and Cherisher of all. Being the sole creator of all humankind Allah is One and is impartial toward His creation. “He has decreed upon Himself mercy” . He provides for all, including those who reject faith in Him, or even those who defy Him. Allah is everybody’s God even though if people don’t turn to Him.. God is continously in concern and protection of all beings no matter what. So Allah protects each and all but those who deny Allah as their protector, they have no where else to go as a refuge because all refuge is only in Allah.
Allah does not do any injustice to the creatures and order justice and good conduct to mankind. He gives equal opportunity and equal rights to every human being irrespective of his chosen belief and religion.. Finally, Allah will surely judge concerning his servants on the day of jugement. But in this life Allah will not forsake any being. Allah provides rain and food and air to those who disbelieve in Him, and created everything on earth and in the heavens for the benefit of the human race. If He stops protecting then all will perish in an instant but Almighty God not only protecting but also has given the freedom so that we could recognise His bounty. Even Allah opens the door and make it prosperous for which they strive in this life.
Thus, Allah love His entire family including believer or unbeliever, we can deny but our structure, features apparently manifest that we all are from One Lord.