At the bottom, the great distinction between true forms of government is that of the individual vs the collective. Of the former, think “Constitutionalist Republic,” of the latter, think “socialism.”
Likewise the issue at hand here. Christ died to save individuals, individuals who seek, and love, truth. Common among Protestants. This, as opposed to the kind of one world syncretism that Romanists promote.
Why discuss secular government? The Church is a different model entirely. The Church, in fact, teaches a doctrine called "subsidiarity", which means that functions proper to individuals or small groups thereof, should not be taken over by larger bodies. Furthermore, temporal governments are necessarily geared to different cultures, countries, languages, geographical areas and ethnicities.
That said, the relevance of this to Ch 17 of John's Gospel, escapes me. The entire chapter is the prayer of Jesus for the unity of His disciples.
Likewise the issue at hand here. Christ died to save individuals, individuals who seek, and love, truth. Common among Protestants. This, as opposed to the kind of one world syncretism that Romanists promote.
We're saved as individuals but there is one God, one Gospel, one Truth and one salvation. All else is error. Hence the difference between temporal governments and the Church.
Read St. Paul's exposition of the Mystical Body of Christ. There is one Body, but within that Body, many different parts, many different vocations. Evangelists, teachers, prophets......but all part of the one body.