Our disunity as a Muslim Ummah is painfully apparent every Ramadan. We cannot agree on when to begin fasting and when to celebrate Eid. This reality is pointed out with glee by the enemies of Islam. Even countries which are neighbours announce the beginning and end of Ramadan on different days. It seems that when it comes to this issue (among a vast array of others), we are still suffering from the historical decisions of the colonial powers which divided our lands (as was the case with the secret Sykes-Picot agreement of 1916, which partitioned the Ottoman Caliphate).
"and that would be part of the dīn of Allah which is obliged for him, just as every responsible person knows from the dīn of Allah what is obliged for him regarding the five prayers, fasting Ramadan, ḥajj and the like"