Role of Christianity in the formation of the world states

From thereon, after Constantine made Christianity the state religion, states in Europe were identified by their Christian nature. The fight of the Catholic Kings in the late 14th century in reconquering Spain from the Muslims is a prime example thereof.
On the other hand, earlier Christian states in the Middle East had to give in and later surrender to Muslim conquerors. The initially benign regime of the Muslims made many Christians easily convert to Islam or accept a subordinate (but respected) position in Islamic state and society.
Some countries, like Armenia and Georgia, however, gained strength from being Christian to withstand outside pressures and hold out over centuries against Muslim forces.
From a European perspective, Christianity was a decisive factor in developing states, becoming stronger and eventually expansionist. States became missionary, may be not from a truly religious perspective, but them being Christian made them proud and claim to have a mission to win other for their own and Gods cause (whereby the order of the two mostly was ‘first the state and then God’).
Christian states in Western Europe (the remnants of the Western Roman empire) inherited a vision on State and Rule of Law that was defined by scholars like Saint Augustine. State and Church both had a role to play, keeping each other in balance. Eastern European countries however, inherited a more Byzantine state view, whereby State and Church were more intertwined, serving the other, culminating in Tsarist Russia (and mirrored in the present Russian state)