All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad  is His slave and Messenger.
  is His slave and Messenger.
Dear brother, we think that you are a Muslim and that you believe in Allaah The Almighty, the Lord and Sustainer of the whole world. There is none co-equal or comparable unto Him. He begets not, nor is He begotten. There are millions of pieces of evidence proving that Allaah The Almighty alone is the true God, worthy of being worshipped. Everything in this world shows that Allaah The Almighty is Alone. You should cling to the way of Allaah The Almighty and His Messenger Muhammad  i.e., the Quran and Sunnah (Prophetic tradition). This is the best way to get success in this life and the Hereafter; do not seek to follow the East or the West.
  i.e., the Quran and Sunnah (Prophetic tradition). This is the best way to get success in this life and the Hereafter; do not seek to follow the East or the West. 
There is no doubt that all the prophets were sent to preach the right way, but many people did not accept their call. This does not mean that this or that message is true or false, right or wrong, just or not. In other words, this does not challenge the rightness or legality of some issue. Since you have heard from numerous scholars, I would like to explain only two points here: 1) Most of the Companions  got married to more than one spouse. A few of them did not get married due to exceptional reasons.
  got married to more than one spouse. A few of them did not get married due to exceptional reasons. 
2) As for the second marriage of ‘Ali  yes, the Prophet
  yes, the Prophet  opposed his marriage for many valid reasons:
  opposed his marriage for many valid reasons: 
 to avoid any action which may harm Faatimah
  to avoid any action which may harm Faatimah  ; consecutively, it may disturb her father, i.e. the Prophet
; consecutively, it may disturb her father, i.e. the Prophet  which is Haraam (impermissible) in itself.
  which is Haraam (impermissible) in itself.  gave his reason for this in the following Hadeeth (narration): “By Allaah, the daughter of Allaah’s Messenger and the daughter of Allaah’s foe should not meet in one house, i.e. as two wives for the same man.” This is also one of the special attributes of the Prophet
  gave his reason for this in the following Hadeeth (narration): “By Allaah, the daughter of Allaah’s Messenger and the daughter of Allaah’s foe should not meet in one house, i.e. as two wives for the same man.” This is also one of the special attributes of the Prophet  .
.Allaah Knows best.