One of the great mysteries of our God is that He is a triune God. We serve one God, but He exists in three persons. He is not three different gods, but the one true God, existing in three persons who are all equal. The Father, Son, and Holy Spirit are of the same essence. There is not space enough here to do an in-depth explanation of the Trinity. My purpose here is to warn against a wrong understanding of the Trinity because it is of vital importance to understanding the gospel.
If you believe the Bible to be the inerrant, infallible Word of God as I do, then we must recognize there are mysteries in it we cannot understand in our humanness. Some day God will make it clear. For now, the Trinity must be something we accept by faith, even though we do not comprehend its possibility.