What is the Holy Ghost?

For most Christians, the Holy Spirit or Holy Ghost is the third person (hypostasis) of the Trinity: the "Triune God" manifested as Father, Son, and Holy Spirit; each person itself being God. However, I will use the scripture to not only prove that doctrine wrong but also explain what the Holy Ghost is, what it was given for, how to receive it, how you will know if you have it, and the divine order of the church. This sermon is essential for Christians who want to understand God and who he really is.