Question:
What verses show that there is a trinity in the Godhead?

Answer:
In John 14:26 Jesus said: “But the Comforter, which is the Holy Spirit, whom the Father will send in My name, He shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.” This verse shows that all three in the Godhead are distinct Persons.

After the Lord rose from the dead, He told His disciples to use the three names of the Godhead when baptizing: “Go ye therefore, and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit” (Matthew 28:19).
In Isaiah 48:16 the Son is speaking and alludes to the Father and the Spirit. “Come ye near unto Me, hear ye this; I have not spoken in secret from the beginning; from the time that it was, there am I: and now the Lord GOD, and His Spirit, hath sent Me.”
The Hebrew word, “Elohim,” which is translated “God” in the first verse of our Bibles, and used elsewhere in the Old Testament, means “three or more” (Genesis 1:26, 3:22, etc.).Another verse where the three names of the three Persons of the Godhead are found is in 2 Corinthians 13:14: “The grace of the Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit, be with you all. Amen.”