The Major Powers in the west favoured the Safavids because they were an obstacle to the Islamic expansion of the Sunni Ottomans i.e. they (Shia Safavids) were one of the major causes why the Muslims couldn’t conquer Europe. Ferdinand, the ambassador to the Austrian King remarked:

“Had it not been for the (Shi’ite) Safavids in Persia, we would have been reading the Qur’an this day like the Algerians”

Meaning that his nation would have been conquered by the Ottoman Muslims. It was the Safavid state that kept the Ottoman state busy with fighting the Safavids, instead of the crusaders. The Safavids had never beaten their western neighbours in a straight fight. Hence Safavid Persia and Europe formed an alliance against the Sunni Ottomans. A dramatic example of this is the role of the English engineer/adventurers, known as the Sherley brothers who helped Shah Abbas create an indigenous musket and cannon industry to fight the formidable Ottomans. Shah Abbas’ personal bodyguard were recruited from the Armenians and the Georgians of the Caucasus. How true is the famous statement of Shaykh Al-Islam Ibn Taymiyyah who more than two centories before the emergence of the Safavid dynasty said:

“The Rafidis are the donkeys of the Jews, they ride them for every fitnah”
[Ibn Taymiyyah, Minhaaj-us-Sunnah 1/20-21]

Those who do not learn history are doomed to repeat it.