Sa lahat ng mga samahan ngayon sa relihiyon, na nag-aangkin na tunay na iglesia, ang Iglesia Katolika lamang ang siyang makapag-patunay na siya ang tunay na samahan na naitayo ng Panginoon, batay sa history o kasaysayan ng mundo.
Ito ang katibayan batay sa Standard References:
"The history of the Roman Catholic Church began in an upper room in Jerusalem almost 2,000 years ago. About 120 persons were gathered there. They were followers of Jesus Christ, and they were awaiting the coming of the Holy Spirit he had promised to send them from heaven. The day on which the Holy Spirit came down is considered the birthday of the Church." (The New Book of Knowledge Vol.16 page 287)
"Catholic Church (Gr. katholikos, universal, general). Term generally applied to the Divine society founded by Jesus Christ, and endowed by the outpouring of the Holy Ghost on the day of Pentecost." (Grolier Encyclopedia Vol.5 page 106)