I can quote the scripture all day long about the marks of the Church, but as St. Francis taught me, it is of limited use.
Christ founded one Church on one rock. Not two and not 20,000. He gave one set of keys to one man, St. Peter, to open one gate, to one heaven. He predicted that the Church will be one again, and we know it will. That is about "one".
He gave His Eucharist and explained that unless one is baptized of water and spirit and eats of His body, he will not go to heaven. He charged the priesthood to feed and guide us. He told us to strive for perfection, to give up the world and follow Him. That is about "holy".
He taught that our Father is love Who wishes salvation of all. He said that the last sheep, the worst sinner, is to be welcomed to the Church as brother. That is "catholic".
He sent his disciples to teach others and to make rules for the world, even as His Father sent Him. The Apostles obeyed: they wrote the gospels, corrected errors and condemned heretics. That is "apostolic".
As always, if any of the above scriptural references are not immediately coming to mind, ask for direct quotes.
You just keep writing lines like this about God's holy Scripture and I won't have to post anything.