And the other thing that such Shuyukh must be careful about is that if they try to present Islam in a "Modern Way," then they can NOT say/call towards Nifaq (Hypocrisy).
Like one example, many of the Modernists beleive that, "It is not obligatory to follow all the orders of Allah and his Rasul (SAW)."
And by saying that, they are also saying that, ""It is not Fardh to follow the way of Rasulallah (SAW); nor is it Fardh (and obligation) to wear the beard (up to a fist) or cover the hair and dress modestly (as long as one who doesn't cover their hair is not "trying to dress in a seductive and vile manner") (even though Rasulallah (SAW) and Allah (SWT) ordered the beleiving men to keep the beard (Ref:Bukhari and Muslim) (and atleast to a fist length (Ref: Ibn Majah)), and the women to wear their headscarves and make it cover their chests) [Surah Noor ( Chapter 24) and Surah Ahzab (Chapter 33)] "
And Rasulallah (SAW) stated (reported by Bukhari/Muslim): "Jannah is for ALL, except for those who refuse. The Sahabi asked, "Ya Rasulallah (SAW), who are those who refuse?" (He, (SAW) replied) Those who accept to follow my Way (of doing things, Sunnatur Rasulallah SAW) are of those who accept Jannah. And those who refuse my Way have refused Jannah (Paradise)."
And so as Beleivers, we must ALL beleive that it is Fardh to obey Allah (SWT) and follow/obey Rasulallah (SAW). So:
-Those who do beleive (in the correct way above), they are from the Mumineen (and whoever falls short in doing the above, then they should make Tawbah (Proper Repentence), because Allah (SWT) will ( باذنه ) forgive them.
-Those who do NOT beleive in the above [that it is Fardh to obey Allah (SWT)/ Rasuallah (SAW) and follow Rasulallah (SAW)'s way], then such a person would be considered a Munafiq.
To learn more, I suggest (maybe the moderators) to look through the Book, Nawaqid al-Iman (By Sh. ibn Abdul Wahab), and also the story of Umar (RA) executing a Munafiq from which Allah (SWT) revealed Ayaat Testifying to Umar (RA)'s innocence.
** As for the "marrying more than one women is concerned," there is no problem with a person marrying more than one women, as LONG AS there are no "side effects," like fighting between the wives, not giving each of the wives their rights, not being just with one's wives, etc.
On the other hand, Allah (SWT) says in the 2nd Ayat of as-Suratun Nisa (Chapter 4: The Women),
"....Marry (other) women of your choice, two or three, or four but if you fear that you shall not be able to deal justly (with them), then marry only one women (whether they are free or if they are slaves). That is nearer to prevent you from doing injustice."