We must not be on the same page, because I see a fairly blatant contradiction there. You don’t have faith in something you know. I know I can’t walk through a wall. I don’t need the hope (expectation) that I can’t – I know I can’t. “and he had faith no longer, for he knew, nothing doubting”…(Ether 3:19)

Regarding my examples: I was referring to this mortal life, if it wasn’t clear. Of course, outside of mortality or with divine intervention many more things are possible – but we’re living in this life, and God isn’t going to make me fly .

With love, it is an instantaneous thing. It is more organic and can change (unlike, for example, “Jesus Christ is the Son of God”), so I probably shouldn’t have used that as an example.

So, let me reframe my situation. “I know I can’t fly by flapping my arms. I know I can’t walk through walls.” as compared to “I know this Church is true. I know Joseph Smith was a prophet of God.” Does my testimony of walls and flying doesn’t need nurtured or room to grow? I don’t think so. Maybe it did when I was a child – but then that wasn’t really knowledge. I don’t need to try walking through a wall every morning to double-check my knowledge. Nor does running into a wall and stopping cold add any substantive testimony to my knowledge that I can’t go through them. I don’t need faith that I can’t walk through it – I know I can’t. It isn’t something fragile that needs to be recaptured daily.

Relating love to knowledge and faith fits well with my take that knowledge involves faith and action, etc.

But even in other considerations as you’ve mentioned, our knowledge of these might not be as secure as you might think. Even this knowledge must be nurtured and given room to grow. A mortal physical body cannot fly nor walk through walls, but apparently a resurrected physical body somehow can (Luke 24:51; John 20:19; JS-H 1:30). I know a man who loved his family very much when he was married, but subsequently committed adultery, “fell out of love,” got a divorce, and now wants to marry his mistress.

Consider the “standard” testimony: “I know this Church is true. I know Jesus Christ lives and died for our sins. I know Joseph Smith was a prophet of God…” This isn’t the whole testimony, I know – but this is certainly the core of a testimony.

Now, consider this quote from President Harold B. Lee, “Testimony isn’t something you have today, and you are going to have always. A testimony is fragile. It is as hard to hold as a moonbeam. It is something you have to recapture every day of your life.” (Church News, July 15, 1972, 4.)

Isn’t this statement at odds with the standard “I know ____” testimony? Things that we *know* don’t need to be “recaptured every day of your life.” I don’t need to reconvince myself that I can’t fly, that I can’t walk through walls, or that I love my family – I know those things.

I agree that we do not know with certainty everything about God – that isn’t quite what I was going for. Let’s look at a “simple” core doctrine that most people would say they know: that Christ died for our sins. For me, my testimony in this specific doctrine is continually strengthened by living in the Gospel, repenting, etc. I’m relatively inexperienced in the Church compared to most other people, but I would propose that most everyone experiences that continual strengthening of their faith and testimony in Christ’s atonement (correct me if I’m wrong here). Doesn’t this suggest that we are not 100% certain? Refer to my arm-flapping story – if we are 100% certain, there isn’t any need for strengthening. Now, some people would probably say that 99% certainty still qualifies for “knowing,” but I’m a little uncomfortable with that notion. How can there be multiple levels of knowing? You either know something, or you don’t. Colloquially we often refer to things we “know” that we really aren’t certain of, but I don’t think testimonies or spiritual truths are the right place for that loose definition of “know.”

“If the Apostles have a greater witness than we do, then what are we doing to gain that same witness ourselves? I think this is what the gospel is teaching us”

I agree. That knowledge and sure conviction is what we should strive for. But that is just like how we strive for perfection in our obedience to the commandments – we strive for it, but we don’t necessarily attain it. The Apostles have a greater witness because they are in a calling that requires it. Similarly, the Apostles have demonstrated great sacrifice and willingness to serve and be obedient to the commandments – probably far past what I have accomplished so far. So much of the Gospel is about eternal progress – why do we feel the need to *know* the truthfulness of things in mortality? As I said before, to know something is, in effect, the perfect state of understanding and belief.

RE: Ether 4:11. I really like that scripture. It does seem to support your viewpoint, but I feel like the qualifications for “knowing” something is true is somewhat variable, and not altogether clear. To be sure, there are lots of scriptures that refer to knowing the truthfulness of certain principles – for that reason, I’m not about to declare my view about this as the hard truth . To quote the Bible Dictionary Entry on knowledge:

“Knowledge of divine and spiritual things is absolutely essential for one’s salvation; hence the gospel is to be taught to every soul. ‘How shall they believe in him of whom they have not heard?’” …”The scriptures, and also living prophets, are given so that the people might have knowledge of things of God and ‘know how to worship, and know what you worship’”

These two quotes seem to point to more of a declarative-fact statement type of knowledge, rather than the intimate knowledge that a testimony of “I know that God lives” conveys. There are other places in the BD entry that refer to the intimate variety of knowledge – I’m not saying that doesn’t exist in the scriptures – I’m just saying I think there is a distinction, and it isn’t exactly always clear which meaning is in use.