I can appreciate your serious concerns, as I am sure others do as well. I remember going through that myself. The real surprise (and answers) will come when you realize that your seeking and inquiring were really God drawing you near all the time, and not so much that you were travel some spiritual labyrinth. You might even find at some later time that the questions no longer need to be asked since you will know the answers as a truth.
 You asked Why? I guess we could answer with some rational and historical arguements about ‘organized’ religions and their system of beliefs (dogma or doctrine). Baptist in particular are well known for their systematic approach to witnessing or explaining points of theology… but each christian sect has its particular traits. Why could be answered, it is a cookie cutter approach: Do this and then this and then this and there you go. We should remember that historically, discerning the saved from the unsaved was serious business. And the expectation to see ‘fruit’ was the eventual true sign.
I think that by the time you discern the answer it will cease to be a question and you will either of decided to do it [publicly] or not. You will simply know (and of course God will too!).
I agree with most of the previous comments that appeal to scripture as to ‘why’, so I don’t have to repeat. And you noticed a few pointed out comments as to why not (ie: you should do it in private). You will eventually see that you can agree with both sides and not necessarily be contradicting cuz each person will decide how public they choose to be with it. In the end, you will be sure.
 You asked If only God knows… do I still? I agree with others who say YES, but by that time you will find it hard to contain yourself anyway, making it a moot point! C.S. Lewis believed that he could simply keep his christianity a private matter (not to avoid the public but he truly saw it as ones private right) and soon discovered that it just doesn’t really work that way. Not out of need, but just as a family member is naturally and unconditionally loving his family and getting that in return cuz he is a part of the family unit. It is natural.
 You asked If someone loves God … do bad things? I like the saying (by ?): God did not come to make bad people good but to make dead people live (similar to Matt 9:12). Also the story of the lady who said: The difference between your faith and mine is that you ask Christ to die again and again for your sins (ie: seeking repentence & forgiveness) while I believe that he died once for all my sins.
I am not trying to downplay repentence but trying to make sense of the act of 2000 years ago at the cross: Christ is not the only one to die at the cross but all christians (and their sins) died there too. If you can picture yourself at the cross, you are the one Christ was speaking to when he said: today you will be with me in paradise (Luke 23:43). He rose; we rose. A new chance; a new life.
Badness, doing bad things, sin, may be our inability to connect with God at times (like in relationships), but the bigger picture is that the relationship has been restored; we are reconciled to Him. That’s the good new. As Christ said he did not come to abolish the law but to fulfill it (Matt 5:17; but compare Eph 2).