Had Allah willed, He would have made you one Ummah

Allah says in the Quran, Surat Al-Maaidah (5:48):
To each of you We prescribed a law and a method. Had Allah willed,He
would have made youone nation [united in religion], but [He intended]
to test you in what He has given you; so race to [all that is] good.
To Allah is your return all together, and He will [then] inform you
concerning that over which you used to differ.
The differences between us, differences of religion, ethnicity and
nationality, are a test and a blessing. They are a part of Allah's
plan. If He had willed it, He could have made us all onesingle Ummah,
with no disagreements and no variations, homogeneous like a field of
grass, all blending together so that the eye could rest on any one
person and he would look no different from any other. Allah could have
made us all with the same language, same faces, eyes and hair, same
customs and traditions, same cuisines, same art and architecture… But
that doesn't sound like a very interesting or exciting world, does it?
The religious differences among us are a test. The other differences
are blessings.
Never let the vast variety of human tongues and traditions become a
source of hostility, suspicion or despair. Never let the physical
distances betweenus become a source of frustration. Be grateful for
the beauty of a Tibetan monastery high in the Himalayas, or the tang
of Thai curry, or the beating of the drum at an Indonesian wedding, or
thegreat variety of cultures found in your own hometown. Be glad for
the opportunity to be exposed to something different, andto let your
mind open like a flower.
If the differences between people present a challenge,then welcome the
challenge; Allah has given you that challenge for a reason, so look
for the opportunity to learn. It is there.