Greetings Smartinez,
I, for one, believe that God will reveal Himself to us in any way He pleases, and that He does not restrict Himself to revealing Himself to us by Scripture.
HOWEVER...While sometimes people do experience the whisperings of our Lord, very often (in some circles, almost always) what they are experiencing is their whim and fancy, or maybe even the whisperings of the enemy, in some cases. There is also always the possibility that they are using testimonies of experiences that they have not had for coercive purposes. Or because they're afraid of what their fellow Christians will think of them if they found out that they weren't experiencing anything (what sadness, fear and isolation to be experiencing within a Christian community!).
I would venture to say that if the person cannot engage in adult, peaceful conversation about it, it is far more likely that it is not the whisperings of our Lord, but one of the other possibilities that I have mentioned above. Be graciously skeptical.
As goes one saying that I have read, "To be ignorant of Scripture is to be ignorant of Jesus". The Holy Bible contains the whole Word of God, but the problem is that we need help with that sometimes, as the mind-boggling number of interpretations of the bible testify. It can and has been read: like a Boy Scout manual of rules, directions and instructions; as a history book; as the intimate, passionate words of a Holy and all-powerful God, saying
I Love You! in every way that it can be said; as the repeatedly self-contradicting diatribe of a bunch of weak, deluded and mislead wackos; as the threat, stated in many ways, of how a distant and wrathful God will punish those who don't tow the line; etc., etc., and in every permutation and combination. There is more to being a Christian than reading the bible; there is an experiential element too.
But all within the context of the Word, of Scripture!So if your experience doesn't jive with scripture, it is probably not of God. Another question to ask is, are others recieving the same message? We are meant to live in community with each other, as all of the "one another"s in scripture testify, and our experiences of God are also within the context of that community. If God tells me something, me alone and to no-one else, I would proceed with caution, if at all (depending on the circumstances). And I also bounce such things off members of my Christian community; if they have a sense that this is not from God, I am skeptical of my "insight", because I trust their discernment. I also trust them enough that Iknow that if I share something that they are skeptical of, they will be straightforward with me without shaming me or diminishing me in any way, but respecting my discernment and humility in bringing my "insight" before them.
I, and people I know, have had experiences of God beyond Scripture. For example: I had long puzzled how a God who loves me so very, very much would want to have me feel like the lowest of the low, as Isaiah (whom He loved) felt when he said "I am a man of unclean lips" (Isaiah 6:5). Why would a loving Father wish to see his beloved child prostrated before Him? I had prayed about this many times. Then, at the end of a very dark day one day, I had this experience that words could never fully describe, but I will try. I had been indulging my addiction all day (no, not heroin

; I play solitaire on the computer

. Don't laugh; this is a real problem for me! It numbs me out, "protects" me from feeling, and while I feel nothing during, I feel more down than ever afterwards. I am terribly embarrased to say, I went 7 hrs straight that day

; time I did NOT have to spare). I was feeling such wretchedness, shame and humiliation, and then the Lord lifted me from that. I had an experience of absolute creatureliness and humility, but at the same time an absolute abscence of humiliation. Never have I felt so loved, so beautiful and so very precious, and so utterly utterly dependent on God. I understood with my heart in that moment, and desired very much to prostrate myself before God. And so I lay on the floor in the hallway, on my face, filled with love and preciousness and humility.
This experience does not contradict scripture in any way, and when I shared my experience with my community, one of our members said, "Wow; that sure sounds like God to me!", and all agreed, and we rejoiced together in the way in which God was working in my life.
I hope that this helps,
In His love,
-Grace