In what sense is the bible is "clear"/perspicuous? What do protestants mean when they say that the bible is "clear"? I would assume that it would mean that people reading the Bible or any part of it generally come up with more or less the same idea of what it says, but that doesn't seem likely to be what protestants mean, because the different protestant cults regularly and consistently dream up radically different interpretations of the Bible as a whole and even different members of the same denomination rarely agree on the meaning of various passages.

I've heard people say that the bible is clear enough that anyone can read it and immediately understand the "Core doctrines", but this is demonstrably false: Protestants don't agree on core doctrines because they don't even agree on what the core doctrines are in the first place. Some people read it and conclude that baptismal regeneration and infant baptism is the go, some people read it and come up with transubstantiation, some people read it and come away denying the trinity, some people read it and think that all you need to do is believe in Jesus to be saved, while other people read it and reckon that you need to do works as well. Protestants say that the Core Doctrines are "salvation issues", but they can't even come to an agreement of what those salvation issues are.

I've heard people respond to this by saying something along the lines of "Scripture is clear, but we are sinful humans and our sin gets in the way of us understanding it", but to me that seems to just come across as a flat contradiction: If scripture is clear, then it should be so clear that our sin doesn't get in the way of us understanding it. However if sin still has the power to cloud our understanding of the bible, then the bible is not clear enough to cut through our sin, and is therefore for all intents and purposes not clear at all.

Taking all this into consideration, what does it mean for Scripture to be "Clear" and "Sufficient"?
This is probably a "no win" situation attempting to answer such a question and this will, in no way, be considered a comprehensive answer for such a simple question that has been so complicated by so many people with so many varying agendas.
Many years ago, one of my Bible professors stated that the best commentary on the Bible is the Bible.  In the nearly 40 years past since then, I have found this to be, "a faithful saying".
That being said, I would like to address this question initially with what God has to say about it:

"The wrath of God is being revealed from heaven against all the godlessness and wickedness of people, who suppress the truth by their wickedness, 19 since what may be known about God is plain to them, because God has made it plain to them. 20 For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse." (Rom. 1:18-20)

Now this passage is referring to 'natural revelation' and not particularly to Scripture but can certainly be construed as establishing a pattern.  If His eternal power and divine nature which can be "clearly seen" through  His creation, is it such a leap to consider that it is equally clear through His word, His divine revelation? The questioner is questioning the how "clear" the Bible actually is.  Peter asserts, " We also have the prophetic message as something completely reliable, and you will do well to pay attention to it..." (2 Peter 1:19).  He also asserts, " Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation of things. 21 For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit." (2 Peter 1:20).

Let's take a moment to consider the "Romans Road to Salvation" (the first part of which has already been noted), as an example, to gauge a level of clarity: 

"For all have sinned, and fall short of the glory of God." (Rom. 3:23), "For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord." (Rom. 6:23), "But God demonstrates His love toward us, in that, while we were still sinners, Christ died for us." (Rom. 5:8) and "That if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved. For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation. (Rom. 10:9,10).

Now one may dispute this, but these verses are pretty clear in their message.  There are certainly passages which are somewhat more ambiguous.  Here is one that has puzzled me for many years, "There were giants in the earth in those days; and also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown." (Gen. 6:4).  In this case the ambiguity is not so much in the text but in the questions it raises.

Now, in light of my initial statement, consider this:  " For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. 22 Although they claimed to be wise, they became fools 23 and exchanged the glory of the immortal God for images made to look like a mortal human being and birds and animals and reptiles.

24 Therefore God gave them over in the sinful desires of their hearts to sexual impurity for the degrading of their bodies with one another. 25 They exchanged the truth about God for a lie, and worshiped and served created things rather than the Creator—who is forever praised. Amen."

Based on this information and years of experience, I feel comfortable making the following statements as to the clarity of the Bible.


The message of the Bible is clear.
Many verses in the Bible are not so clear.
God Himself has stated that there are those who purposely exchange "the truth about God for a lie...)
When someone says, "The Bible is clear on this topic.", the legitimacy of that statement would depend greatly on the topic.
Though the Bible is clear in its message, the continual efforts of those who would 'put a lie in its place' or interpret it to their own benefit have confused many. 
I would not want to be one of the culprits referred to in verse 5.