Do Jehovah's Witnesses believe in the Trinity?

TL;DR:

The Jehovah's Witnesses believe that the God of the Bible is Jehovah; however, they do not believe in a biblical Trinity. The Bible teaches that all three persons of the Trinity comprise the One God known also as the Godhead—three in One.

what does the bible say?

Although Jehovah's Witnesses claim they worship the one true and Almighty God, the Creator, whose name is Jehovah, they believe that Jesus is a created being and is not Almighty God, because they believe that God cannot die. This directly contradicts Scripture, which teaches that Jesus is fully God (John 1:1; John 20:28; Titus 2:13) and that He truly died for the sins of the world (Romans 5:8; 1 Corinthians 15:3; 1 Peter 3:18).

Jehovah's Witnesses teach that the Holy Spirit is God’s power in action, his active force, but not God. This conflicts with biblical passages showing that the Holy Spirit has personal attributes, including emotions and will, and can be grieved and quenched (Ephesians 4:30; 1 Thessalonians 5:19; Acts 13:2).

Overall, Jehovah's Witnesses teach that there is no Scriptural basis for the Trinity doctrine. While the word Trinity does not appear in the Bible, the truth it summarizes—that the one true God eternally exists as three distinct Persons, Father, Son, and Holy Spirit—is clearly taught through the combined witness of Scripture (Matthew 28:19; 2 Corinthians 13:14; John 1:1–14).

from the old testament

In Genesis 1:1 God created the heavens and the earth with the assistance of the Spirit who moves over the surface of the waters. A reference to two Beings. The Hebrew word for God (Elohim) indicates a plurality.
Genesis 1:26 says, "Then God said, “Let us make man in our image, after our likeness. And let them have dominion over the fish of the sea and over the birds of the heavens and over the livestock and over all the earth and over every creeping thing that creeps on the earth.” This verse also shows at least two beings present at creation.
Genesis 11:7 says "Let us go down..." to see what the people have done on the plain on Shinar, and confuse their languages. This indicates a plurality.
The Angel of the Lord is often associated with the LORD God and is probably the pre-incarnate appearances of Christ. (Genesis 16:7-13, Exodus 3:2-6)

from the new testament

At Jesus baptism in Matthew 3:16-17 the scene is described as God the Father speaking, the Son being baptized and the Spirit descending like a dove. All three members present.
The account of Ananias and Sapphira in Acts 5:1-8 describes the people lying to the Holy Spirit in verse 3 and equating that with lying to God in verse 4. And in verse 9 Peter says "they agreed to test the Spirit of the Lord." You cannot test a force; you test a being, in this case God.
In Romans 8:12-17 Paul reminds the believers that the Spirit witnesses with our spirit that we are children of God.
We can quench the Spirit. 1 Thessalonians 5:19
We can grieve the Spirit. Ephesians 4:30 This verse indicates the Spirit has emotions.
Revelation 1:17-18 says, "When I [John] saw him, I fell at his feet as though dead. But he laid his right hand on me, saying, 'Fear not, I am the first and the last, and the living one. I died, and behold I am alive forevermore, and I have the keys of Death and Hades.'" Notice that Jesus is the first and the last (Alpha and Omega) and that he died and is now alive. This clearly describes a God who could die, and He did so for our forgiveness.
Jesus said He would have to go away so the Helper could come (John 14:16, 26). This Helper is a counselor and advocate for the believer. A force does not comfort; a person does.
The Holy Spirit gives believers spiritual gifts (1Corinthians 12).
John 1:1, 14 and Colossians 1:15-16 clearly describe Jesus as God who created all things.

implications for today

The Jehovah's Witnesses are a very diligent group, anxious to spread the news of the coming kingdom of God. But their god does not line up with the God of the Bible because they do not accept that Jesus is God, nor do they believe the Spirit is a Person. Their website is full of biblical references and Bible teachings, but generally, they do not permit their members to read any other materials.

This is why it is important to have conversations with Jehovah's Witnesses, reaching out to them in love by showing them that Jesus was completely God and able to pay the price for sin because He was the perfect sacrifice. This should be our goal. We should be teaching them what Scripture teaches about God: Father, Son, and Holy Spirit.

The one main doctrine that separates Jehovah's Witnesses from Christians is their belief that Jesus is NOT God. If Jesus was not fully God He could not be the perfect sacrifice for sin. Their denial of the Trinity rejects biblical teaching on salvation and has implications for their eternal destiny.

understand

Jehovah's Witnesses believe that Jesus is a created being and is not Almighty God.
Jehovah's Witnesses believe that the Holy Spirit is not a personal being and not God.
Jehovah's Witnesses are not a part of true Christianity because they do not accept the three-in-one Person of God.

reflect

How do you view and explain the Persons of the Trinity?
What are the implications of rejecting Jesus as being fully God made flesh?
What characteristics of the Spirit are most comforting to you?

engage

Why does it matter that we believe in the Trinity?
How can we help our unbelieving friends see the truths and implications of the Trinity?
What should we learn from Scripture that will help us better witness to cults like Jehovah's Witnesses?