When I read in Matthew chapter 3 verse 16 and 17, I realize the power of the Trinity. At that one moment when Jesus is baptized by his cousin John the Baptist we were able to see the spirit of God / the Holy Spirit in the form of a dove travel from heaven to earth. We also were blessed enough to hear the voice of God when he said "This is my son, whom I love; with him I am well pleased." And of course we were able to see Jesus when he was being baptized.
If you are like me, there are times when I think about the Trinity and I become overwhelmed with the emotion of joy. Yet there're other times when I can't help but be confused. My earthly mind wants to understand how one can be three. The longer I have been walking with God the less important it is to comprehend the mystery of the Trinity. When I say comprehend I mean fully understand. Perhaps what I used to think as being in need of understanding in order to fully believe in the power the Holy Spirit has given the way to the wisdom that can be gained by simply having faith that what God tells us in the Bible is the only truth we need. You see, to me I have learned that it is not a requirement to understand everything in order to have the faith that God wants us to have in Him. Not having to fully understand the Trinity (for example) but trusting that it is true is in fact having a leader that you ultimately trust.
I am thankful that my leader happens to be the creator of the universe. In my humble opinion, that is enough of a resume for me to trust Him without having to understand everything about him.