I'm speaking in general terms of knowing. In the epistemological sense. How do we know what we know. Remember, according to my definition (which I think is correct) to know is "being personally convinced of the truth of something." So I can know things apart from God's Spirit. Atheists know things that are true. I'm not just speaking of Spiritual truths or truths of the faith. I'm speaking of knowing in broader terms.
I'm sorry, I guess I cannot follow you down this road. I do not think that we know anything apart from God - spiritual or not. I am not sure if that is where you are at with this, but I do not think that anything is known apart from God giving a person the ability - spiritual or not.
I think that all 'knowing' comes from God. I think it is He who gives you the ability to know. I know some people think that God created everything, set it in motion, and then is letting things 'evolve'. I believe He works in the world each and every day, every moment of the day.
So Atheists may know things that are 'true', but its only because God has given them that ability. When they do not believe something is true, when it actually is, they are simply denying the truth being given to them.
With the example you gave in regards to baptism and your earlier beliefs, I do understand what your saying. I was there too, but when I believed some things there was always some doubt. There is some doubt now about things I am sure. I would not declare to know something is true if I had doubt about it.
I think you can be 'convinced' and pretty sure about something - believing it is the best probable answer to a question - but when you know the actual 'truth' of something, there is no denying it is truth - it is absolute in your mind. No one or nothing could possible convince you that it is not truth. Its not a matter of not letting others try to convince you, or not listening to others idea's about something, its just that when you do hear other things you 'know' that they are not true.
I know that this discussion started with the whole OSAS talks going on, so its natural to use it as an example. I have been around the block in regards to it. One end of the spectrum to the other, I have at one time 'considered' them all.
I can tell you with absolute certainty, zero doubt, that what I know is true. I know its true because I can say I have no doubt, its not that I might have it wrong, its the fact that I have had it wrong in the past and I knew then that I did not have the truth.
The problem is not that truth is hard to understand, it is that truth is hard to accept. When you accept the truth, you have to lay aside all of your own presuppositions. Humans are corrupt, you can consider our thoughts as a bottle of poison. If you mix your thoughts, even one drop into a glass full of truth, the glass becomes corrupt. It does not make it true because 99% of it is true. One bit of something false makes everything else it is combined with false.
Truth ONLY can come from God. When we think that we can 'know' truth apart from God, then we have fell right back into(or never come out of) the original lie told to human kind.