You can say what you want but biblical proof is the only truth I follow.
Look I have catholic friends including Priests. I have also shared the gospel with catholics that were unsure of salvation and seen them come to Christ. I am Pastor and firmly planted on The Rock, Jesus. I don't want to part of a catholic bash-fest. But it is clear that too many catholics are not saved and it is because of Roman Catholic Church teaching. God's grace [gift of salvation], Jesus finished payment for sin and faith alone in the first two must replace the doctrines of religion the RCC holds or the judgment of God is sure. I have a heart for the lost and that includes lost catholics. You must know that many catholics live lives that prove they do not know and have Christ. That is not a criticism. It is a challenge to do something about it in the RCC. These people will be lost for eternity. For the love of God, help them!
Pot: Kettle -- Black
If you have read the Catechism, you would know that the entire thing is based on Scripture. For every point, there is a Scripture reference. Every doctrine has been derived from Scripture. I'm not saying that you are not telling the truth about having read it, but your whole post doesn't compute, because if you had read it you wouldn't be saying the things you are saying.
As far as "Biblical Proof" goes, there are many points of Scripture which are very plain and clear and which Protestants either dismiss, ignore, interpret with far-fetched interpretations, or argue that the plain and simple words don't really mean what they say (as if they can read the mind of the writers of Holy Scripture or even of Jesus Himself!)
Catholics "come to Christ" every time they come to Mass - in hearing the four Scripture readings and in receiving Jesus in the Blessed Sacrament. If Catholics are "not saved" it is because they don't believe in Jesus, not because of the teachings of the Church - which proclaim Christ in everything! If they are unsure of their salvation, it is because they don't trust themselves, not Christ or the Church! Even Protestants are aware of the term "backsliding."
Catholics believe that Jesus paid for our sins, but we must still be purified. The doctrine of "Faith Alone" is UN-Scriptural (see the second chapter of the Letter of St. James):
"So faith by itself, if it has no works, is dead." James 2:17
"You see that man is justified by works and not by faith alone." James 2:24
"For as the body apart from the spirit is dead, so faith apart from works is dead." James 2:26
You said, "faith alone in the first two must replace the doctrines of religion the RCC holds or the judgment of God is sure." How can you be positive that you aren't the one who is wrong? Sorry, but your statement seems to be quite arrogant and judgemental.
For every Catholic who "lives a life unworthy of the Gospel" there is a Protestant who doesn't either, so it cuts both ways!