Why must a Muslim not wash his private parts after passing wind (gases and vapor) and suffice with ablution for prayer, and is everything narrated from the Messenger of Allah, peace and blessings be upon him, authentic, bearing in mind that the madhhabs did not exist during the time of the Messenger?

The claim that jurists divided the Ummah is false, for the differences among them are a mercy and a breadth for the Ummah. The Companions, the Successors, and the Imams all agreed on the permissibility of taqlid (definition) (following a qualified scholar) for those unable to perform ijtihad (definition) (independent reasoning). The differences in ijtihad among scholars do not spoil affection, nor are they to be rejected by force; rather, they are discussed with scholarly proofs. And it is from Allah's mercy that He appointed scholars for the Sunnah (definition) who distinguished authentic hadiths from weak ones, and to them one refers in this matter. As for wind, it is pure by consensus, and its emission does not necessitate istinja (definition)' (washing after relieving oneself). Rejecting the rulings of Islamic law with mere intellect is not characteristic of a Muslim.