salam alaikum bro
1st of all I would llike to say do not argue with the fasiqoon - state the Truth of the Quran and then leave them with it. If they reject it then it is their own affair.
However that being said I will give you a few arguments against their arguments since you have asked for help.
I looked at their forum thread and saw somethings which you can address:
1. Quran only mentions the 5 times prayers. No mention of any sunnat prayers but still people do. Isnt it spiritual?
The Sunnah prayers are optional prayers - If one prays to Allah swt more they are dearer to him and Alhamdolillah none was dearer to Allah than our Prophet(sa)
2. Why are women prohibited from praying during menstruation when God doesnt? Spiritual?
Allah swt prohibits us from praying in a state of impurity.
5:6 O ye who believe! when ye prepare for prayer wash your faces and your hands (and arms) to the elbows; rub your heads (with water); and (wash) your feet to the ankles. If ye are in a state of ceremonial impurity bathe your whole body.
science has clearly proved that during the menses the womans body is cleansing itself. Thus the discharge given off is impure and unclean. That is why women are in a state of impurity when in menses. And this state of impurity is 'continuos' since the discharges continue, but once they stop they can bathe and pray once again. Thus they are not allowed to pray during their cycles.
3. Why are women forced to cover their faces or wear hijab? God doesnt prohibit.
Women are not forced to do anything in Islam and neither are men.
Islam is a deen for those who believe in it - those who dont can do whatever they want. The Hijab is clearly commanded in
O prophet! tell thy wives and daughters and the believing women that they should cast their outer garments over their persons (when abroad): that is most convenient that they should be known (as such) and not molested: and Allah is Oft-Forgiving Most Merciful.
4. Why is prophet muhammad's name added in the prayers, when the basic kalma or faith in the quran is 'there is no god but God'? only
This is clearly commanded in:
Allah and His angels send blessings on the Prophet: O ye that believe! send ye blessings on him and salute him with all respect.
5. Additional wudu steps not supported by the quran
Neither does the Quran state what to say in Sajdah, nor in Ruku nor in any other posture...would they like to explain what they say in those postures? Anything they like?
Prophet was forbidden from explaining the Quran...
"This (Quran) is the utterance of an honorable messenger. It is not the utterance of a poet; rarely do you believe. Nor is it the utterance of a soothsayer; rarely do you take heed. A revelation from the Lord of the universe. HAD HE EVER UTTERED ANY OTHER RELIGIOUS UTTERANCES (attributed to us), we would have punished him severely, then we would have stopped the revelation to him (fired him). None of you could have protected him against us." (69:40-47)
This is obiviously not a prohibition but in fact the clear evidence that the Prophet (sa) neither said nor did anything except what was commanded to him. That is why we follow the Sunnah. The same people who carried the Quran forward and fought for Islam are the same people who also carried the Hadith forward. And Alhamdolillah Allah swt has given us the knowledge of the deen through the Quran and the understanding thrugh his Rasool (sa)
As for their dispute that one should not follow the Adadith then ask them to explain these verses in TODAYS world's timeline - when the Prophet is no longer alive.....
He who obeys the Apostle obeys Allah: but if any turn away We have not sent thee to watch over their (evil deeds).
Say: "If ye do love Allah follow me: Allah will love you and forgive you your sins for Allah is Oft-Forgiving Most Merciful."
Say: "Obey Allah and His Apostle"; but if they turn back Allah loveth not those who reject Faith.
It is not fitting for a Believer man or woman when a matter has been decided by Allah and His Apostle to have any option about their decision: if anyone disobeys Allah and His Apostle he is indeed on a clearly wrong Path.
Furthermore ask them - if they do not follow the explanation given to us via the Hadith of the Quran and Islam then whose explanation do they follow?
Indeed Allah swt has distinguished the believers from the disbelievers through the sunnah of our Prophet (sa)
ALLAH HU AKBAR