1..The Catholic Church gave us the Gregorian calendar which we all use today.

2.The Catholic Church gave us the date for Easter.

3.The Catholic Church gave us the date for Christmas which means Christ-Mass.

4.The Catholic Church compiled the Bible.

The remains of all of the Apostles are in Catholic Churches, and so are all of the Gospel writers. Note! Some relics are divided between Catholic Churches.
St. Peter is in St. Peter's Basilica in Rome.
St. Paul is in St. Paul's Church in Rome.
St. Matthew is in the Cathedral of St. Matthew in Messina, Sicily.
St. James the Greater is in St. James Church in Compostela Spain.
St. James the Less (the Just) is in the Basilica of the Holy Apostles in Rome.
St. Bartholomew is in St. Bartholomew-in-the-island Church in Rome.
St. Andrew is in the Cathedral of Amalfi in Italy.
St. Philip is in the Church of the Dodici Apostoli in Rome, Basilica of the Holy Apostles.
St. Simon is in the Vatican, under the Altar of the Crucifixion.
St. Jude is in St. Peter's Basilica in Rome.
St. Thomas is in the Cathedral of Saint Thomas in Mylapore, India.
St. Matthias is in St. Matthews Abbey in Trier Germany, and in St. Mary Major Basilica in Rome.
St. John is in the ruins of the Basilica of St. John in Ephesus Turkey.
"You are built upon the foundation of the Apostles and Prophets with Jesus Christ Himself as the Chief Corner Stone."
Ephesians 2:20.
Even though he was not an Apostle, he did write the Gospel of Mark.
St. Mark is in St. Mark's Church in Venice, Italy.
Even though he was not an Apostle, he did write the Gospel of Luke.
St. Luke is in the Basilica of Santa Giustina in Padua, Italy.
The first Christian Martyr. Acts 7:60
St. Stephen is in Rome in the Basilica of St. Lawrence Outside the i.
The first person to arrive at the tomb of the Risen Christ. John 20:1
St. Mary Magdalene is in the Basilica of St. Maximin in Villalata, France.
He produced the first Bible containing both the Old and New Testaments, the Latin Vulgate. St. Jerome is in St. Mary Major Basilica in Rome.
We know from the many authentic Relics that the Catholic Church has in its possession. Among them are:

1. The Relic of the True Cross on which Jesus Christ was crucified. John 19:17-18

2. The "INRI" inscription from the True Cross, called "Titulus Crucis". John 19-19

3. The Nails which held Jesus to the cross. John 20:25

4. The Lance Point of Saint Longinus which pierced the side of Jesus. John 19:34

5. The Crown of Thorns and the individual thorns from it. John 19:2

6. The Table used at the Last Supper is in St. John Lateran Basilica in Rome. Matthew 26:20

7. The Scala Santa, the steps which Jesus Christ ascended on His way to meet Pontius Pilate.

8. The Chains of Saint Peter, in the Church of St. Peter in Chains in Rome.
Many more.........

We know from its sheer Size and Rapid Growth, with over 1,057,000,000* (one billion, fifty-seven million) members, or one in six of the entire population of the earth, as of February 2000. That is an increase of over 40,000,000 (forty million), since December 1997, more than half of the total membership of the largest single non-Catholic denomination. In 2001, the Catholic Church grew to over 1,070,540,000* members, plus another 216,000,000* Orthodox. Bar none, the Catholic Church is the fastest growing Christian Church in the world. All of the over 36,400 various Non-Catholic denominations, collectively added, total less* than the Catholic membership.
For those detractors of the Catholic Church who say that numbers are irrelevant, they are in effect, saying that Satan is winning souls and that GOD is losing souls. They are saying that more people are convinced by the lie from the father of lies, John 8:44, than they are convinced of the truth of GOD, John 14:6. They have forgotten, or maybe they never knew, that Satan can only do what GOD allows him to do.
2014 report
According to the latest statistics from Fides news agency, the number of Catholics worldwide increased by more than 15 million!!!
The statistics show that on that date the number of Catholics in the world stood at 1,228,621,000, reflecting a worldwide increase of more than 15 million compared to the previous year.