know these things of yourself

Alma 5:46
Behold, I say unto you they are made known unto me by the Holy Spirit of God. Behold, I have fasted and prayed many days that I might know these things of myself. And now I do know of myself that they are true; for the Lord God hath made them manifest unto me by his Holy Spirit; and this is the spirit of revelation which is in me.

In this chapter it asks a lot of questions about whether or not you are ready to stand and face our Creator. It talks a lot about what we need to do in preparation for the judgement day. It warns us about pride and also tells us that gaining a testimony is very important. That is what this scripture is telling us. If we aren't sure about the gospel we need to pray, study the scripture, attend church, fast and pray about if this is the true gospel and if the Book of Mormon is correct. If we do this with a sincere heart and have prepared ourselves to receive the answer I believe that our Father in Heaven will reveal to us, just as he did to Alma, that the Book of Mormon is correct and that this church is true.