What you refer to is a corrupt notion that these people believe in as a result of their ignorance of the true nature of Allah’s might and power. Their citing of the hadith which speaks of Allah’s descent to the lowest heaven to support their view is due to their ignorance of the true nature of Allah’s descent and, before that their ignorance of their Lord, may He be exalted, and what is appropriate to ascribed to Him of majestic and noble attributes.
To explain further, Allah’s might and power are not connected to that which is impossible in and of itself; rather they are connected to what is possible – or probable.
An example of the impossibilities that have nothing to do with the might and power of Allah is the notion of Allah taking a partner, spouse or child, because for such things to exist is a shortcoming that is not befitting to Allah, may He be glorified and exalted. Allah, may He be exalted, says (interpretation of the meaning):
“[He is] Originator of the heavens and the earth. How could He have a son when He does not have a companion and He created all things? And He is, of all things, Knowing”
What Ahl as-Sunnah believe is that the might and power of Allah, may He be exalted, have nothing to do with that which is impossible, because He is the most perfect and that [i.e., having a partner, etc.] is a shortcoming that is not befitting to the Lord, may He be glorified and exalted. How can He be the Lord, unique, One, the Eternal Refuge, then have a partner?!
How could He be the Lord, then need a spouse and child?!
Something similar may be said with regard to what the questioner mentioned about these ignorant people who believe that the might and power of Allah are connected to what they mention of impossible things, namely that Allah may enter into some of His creation. This is a shortcoming that Allah declared Himself to be far above, for He – may He be glorified and exalted – is far above all created things, separate from them, and risen above His Throne.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
Undoubtedly Allah is able to do all things, as the Qur’an tells us in more than one place. But what is impossible in and of itself is nothing, according to the consensus of rational people. So according to rational thinking, it cannot exist out there. For example, it makes no sense that out there a thing may exist or not exist at the same time, or may be moving and not moving at the same time, or that successive parts of movement may exist at the same time, or that today exists with yesterday and tomorrow at the same time, and so on.
End quote from as-Sadafiyyah (2/109).
Shaykh Muhammad ibn Saalih al-‘Uthaymeen (may Allah have mercy on him) said:
What is impossible is nothing, let alone thinking that it is possible to do it. Rather the impossible that one could think is impossible is of two types:
As for that which is impossible in and of itself, it is impossible and cannot be. If someone were to ask: is Allah able to create another like Him?
We would say: This is impossible, but Allah is able to create a creation greater than the creation that we know now. We know now that the greatest created thing that we know is the Throne, for the Throne is greater than all other created things that we know, yet despite that, we know that Allah is able to create something greater than the Throne. But the thing that is impossible in and of itself is not possible at all.
The second thing is that which is impossible because of other reasons, which means that Allah, may He be exalted, has decreed that this thing should be in accordance with a certain, consistent way and it is impossible for it to happen in a different way, but Allah is able to make it happen in a different way.
Here we may note that Allah’s power is applicable to that thing, so the thing that we think is impossible, based on the way things usually are, could be changed by divine might and power. Many things come under this category; all the tangible miracles of the Prophets come under the heading of things that are impossible because of other reasons. The splitting of the moon for the Prophet (blessings and peace of Allah be upon him) is impossible for other reasons, not in and of itself, because it happened and Allah is able to cause the moon to split into two halves; indeed, He is able to cause the sun to split into two halves.
We say that there should be further discussion on this matter: that which is impossible in and of itself is not subject to divine power, because it does not exist; it is not possible for it to exist and it is not something to be assumed.
End quote from Sharh al-‘Aqeedah as-Safaareeniyyah (p.192).
With regard to their error having to do with the descent of the Lord, may He be blessed and exalted, that is because they think that Allah’s descent is like the descent of created beings. When they likened Him in their minds to His creation, they thought of what results from descending for humans, such as becoming part of a new environment and becoming lower than that from which he descended, and they thought that this is what was meant by Allah’s descent.
This is a corrupt understanding and false belief. Allah, may He be exalted, says of Himself (interpretation of the meaning): “There is nothing like unto Him” [ash-Shoora 42:11]. This is sufficient to highlight the fact that His descent to the lowest heaven in the last third of the night is not like the descent of His creation. This is what should be believed with regard to all the divine attributes, such as Allah’s rising over (His Throne – istiwaa’), His wrath, His Countenance, His Hands, His knowledge, His mercy and so on. There is no differentiation between His attributes and actions; rather they are all equal in terms of not being like the attributes and actions of any one of His creation.
From what we have mentioned it will become clear to you – if Allah wills – how these people’s understanding is flawed and the dire consequences of their belief concerning their Lord, may He be exalted, and how you can respond to them.
See also the answer to question no. 39679.
And Allah knows best.