God Gives Us the Holy Ghost - Why?

In 3 Nephi 28:11, Jesus teaches: "And the Holy Ghost beareth record of the Father and me; and the Father giveth the Holy Ghost unto the children of men, because of me. "

The Spirit testifies of the Father so that we might know Him, our relationship to Him, and his love for us. That is one of the primary purposes of the Holy Ghost.

God gives the Holy Ghost to us because of Christ. The simple way to look at this is that we would have no real need for the Holy Ghost if not for Christ. If fallen man had no hope of redemption then why send him help? But we do have hope of redemption through Jesus Christ; and for this reason, God has given us the Holy Ghost to help us recognize Christ's teachings, believe in Him as our Savior, and follow Him on the straight and narrow path that leads to eternal life.