Catholics argued that the one built by Christ is the Roman Catholic Church not the Iglesia ni Cristo because the
Iglesia ni Cristo emerged only on 1914 in the Philippines while the Roman Catholic Church existed already before other church started to exist.
These people simply are confused about the Iglesia ni Cristo. Iglesia ni Cristo is a Filipino term for "Church of Christ". And just like what I wrote in my previous post, the Church of Christ that emerged in the Philippines in 1914 is one and the 3rd group among the
3 groups of members of the Church of Christ.
If you'll examine the Bible, Christ in Matt 16:18 mentioned that He would built His own Church. Remember, the church that Christ would built is His own Church not the Roman Church. Christ call this church His Church and Apostles call it Church of Christ.