That is your opinion, and you are entitled to it.
But Catholics believe God did not just toss down a Bible 2000 years ago and leave the world. Christ founded a Church, an institution of men, which is guided in its decisions by the Holy Spirit. The Catholic Church is the only religion in the world with a centralized authority that has lasted for longer than any nation on Earth. It is has survived Roman Emperors, Communist dictators, and the Nazis. It will also survive modern secularism, which seeks to undermine it from within.