I’ve wondered this many times myself. I agree that the Church, on a parish and individual level does a truly horrible job. I attended eight years of Catholic primary school and learned very little about why Catholics believe what they believe. I did not even begin to understand the concept of true Christianity until I began to be confronted by Protestant anti-Catholics when I was in college. This forced me to begin to research and learn about my faith. At that time, I discovered that the Church does contain the Truth of God. However, I would never have discovered this had I relied on the priests and lay leadership. So many of them are filled with deception. Many, for example, believe that we, as Catholics, actually do pray TO Mary. Many have no idea what the true meaning of the Eucharist is or why we do it.
The only way I can think to explain it is that since the Catholic Church is the one, true church of God, that it is under special attack by Satan. Satan has targeted the Church for destruction, though we know that the gates of hell will not prevail against it. However, that does not mean that Satan will not inflict serious damage upon the Church. He has and will continue to do so. Here is a selection of Bible verses which I believe relate to this idea:
1 Timothy 3:1-7:
1 But realize this, that in the last days difficult times will come.
2 For men will be lovers of self, lovers of money, boastful, arrogant, revilers, disobedient to parents, ungrateful, unholy,
3 unloving, irreconcilable, malicious gossips, without self-control, brutal, haters of good,
4 treacherous, reckless, conceited, lovers of pleasure rather than lovers of God,
5 holding to a form of godliness, although they have denied its power; Avoid such men as these.
6 For among them are those who enter into households and captivate weak women weighed down with sins, led on by various impulses,
7 always learning and never able to come to the knowledge of the truth.
21 "Not everyone who says to Me, ‘Lord, Lord,’ will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter.
22 "Many will say to Me on that day, 'Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?'
23 "And then I will declare to them, ‘I never knew you; DEPART FROM ME, YOU WHO PRACTICE LAWLESSNESS.’
See to it that no one takes you captive through philosophy and empty deception, according to the tradition of men, according to the elementary principles of the world, rather than according to Christ.
2 Thessalonians 2:11
For this reason God will send upon them a deluding influence so that they will believe what is false,