The bible was canonized by the Church. If the Church has always been corrupt, then the bible is too.

Not always.

Can the Church, even despite the sins of its members, still teach that Christ is Lord?

Yes.

It is in this context I claimed that the Church has to be free from error in teaching. Otherwise where comes our faith?

Well, the Church seems to think no matter how depraved it becomes God will always be in it, so that's an error of teaching.

But you claim yours based on human judgment.

Do I? (2 Tim 2:12 *"If we patiently endure pain, we shall also share His Kingship; "If we disown Him, He will also disown us *)

You have been conflating teaching integrity with moral integrity.

So you admit the Church doesn't have moral integrity, but expect me to believe all of its teachings are correct anyway? So if a preacher stands up and tells you: "I have no moral integrity. I take bribes, I do this, I do that, I don't follow my own teachings... but I still have teaching integrity and my teachings are all correct", would you believe him?

To be devout means to do whatever God's teaching commands us to do. But when we don't know which one is the right teaching,

The Bible spells it out for me. I don't actually need other people or a Church to tell me what the Bible means when it says: "Do not murder" or "Love thy neighbour" or "homosexuality is an abomination unto God".

We, on our own authority, will declare that homosexual marriage is fine, that abortion is fine, that contraception is fine, and so permit all those things.

Some will, some won't. Just like in the church, since even people in the church support homosexuality.

if there is no church to preserve the right teaching, we will never be devout.

Love the Lord thy God; Love thy neighbour as thyself; do not murder; do not steal; do not commit adultery; do not make a false god; do not covet; honour your father and mother; honour the Sabbath; you shall have no other gods before me; etc.

If the church were destroyed tomorrow, so that there were no churches left anywhere in the world, the truly devout would simply open their Bibles, read them, and there would be the correct teachings sitting right in front of them.