Senior Muslim scholar, Shaykh Saalih ibn Fowzaan al-Fowzaan (may Allaah preserve him) was asked:
There is a famous preacher whose work reaches all over the world. He says that Allaah is not able to do all things. He also says that he knows of a thousand things which Allaah, the Most High, cannotdo. Is this (person considered) a caller at the gates of Hell? Must we warn against him?
The shaykh replied:
This (person) is a Mulhid (deviant) , the one who says these things is a mulhid(deviant) regarding the Names and Attributes of Allaah.
ولله الأسماء الحسنى فادعوه بها وذروا الذين يلحدون في أسمائه سيجزون ما كانوا يعملون
“And to Allaah belong the most beautiful Names, so call upon Him using them. Abandon those who commit ilhaad (deviate)  regarding His Names. They shall be recompensed for what they do.” 
إن الذين يلحدون في آياتنا لا يخفون علينا أفمن يلقى في النار خير أم من يأتي آمنا يوم القيامة
“Verily, those who commit ilhaad regarding our aayaat (verses, signs) are not hidden from Us. Is the one cast into the Fire better than one who attains safety on the Day of Judgment?” 
Someone says that Allaah is not able to do all things… Exalted be Allaah! Allaah says:
والله على كل شيء قدير
“And Allaah is able to do all things” 
How many Verses have [what means]: ”And Allaah is able to do all things,” or,“Verily Allaah is able to do all things”? How many Verses!? 
Allaah has not mentioned any limit to His Divine Ability, (He has) unrestricted Capability, over all things. (He is) able to do all things. He is Knowledgeable of all things. He, the Exalted and Most High, has not mentioned any limits.
And you come and limit this?! Would you say, “No, there are some things that Allaah does not know, and I know them!” 
This is a kind of ilhaad  regarding the Names and Attributes of Allaah.
It is not that every preacher is upon truth. Listen to the speech of the Messenger:
دعاة على أبواب جهنم
“Callers at the gates of Hell…” 
It is not that every preacher is upon truth. [End of Shaykh al-Fowzaan’s words]
Source: This audio recording (Arabic).
Translation and footnotes: Moosaa Richardson
 A mulhid is someone who commits ilhaad regarding the Names and Attributes of Allaah, by either rejecting them outright, or by twisting their meanings in ways not befitting to Allaah. Ilhaad also includes naming Allaah with names that He has not used for Himself. See Exemplary Principles of Shaykh Ibn ‘Uthaymeen (p.49-50). The word “mulhid” could also be translated as “disbeliever” or “rejecter” in this passage, and Allaah knows best.
 Soorah al-A’raaf [7:180]
 Soorah Fussilat [41:40]
 Soorah al-Baqarah [2:284]
 There are over 35 Quranic passages with these or very similar wordings! See: 2:20, 106, 109, 148, 259, 284, 3:26, 29, 165, 189, 5:17, 19, 40, 120, 6:17, 8:41, 9:39, 11:4, 16:77, 18:45, 22:6, 24:45, 29:20, 30:50, 33:27, 35:1, 41:39, 42:9, 46:33, 48:21, 57:2, 59:6, 64:1, 65:12, 66:8, 67:1, 85:16. (As listed in this article.)
 Notice the shaykh mentions knowledge in this example. He likely intended to show how clearly unacceptable it would be to claim that Allaah does not know everything, and someone claims to know some things Allaah does not know! So similarly, any Attribute of Allaah that He has affirmed for Himself, like Knowledge, Ability, or anything else, may not be restricted, limited, or specified by rationale or philosophy. And Allaah knows best.
 From the authentic hadeeth of Huthayfah foretelling the people of deviation and their tribulations to be faced by people in later times (meaning): “There will be callers at the gates of Hell, and they will cast anyone who responds to them into it…” It was collected by Al-Bukhaaree (no.7084) and Muslim (no.1847).