Responding to the Jehovah’s Witness attacks on the deity of Christ

If Jesus is God, why did he pray to the Father in John 17?

Jesus prayed to the Father because as a man, under the Law (Gal. 4:4), he needed to pray to the Father.  The Bible teaches that he was both God and man (Col. 2:9; John 8:58 with Ex. 3:14).  Also, Jesus has two natures.  Therefore, we will see two types of scripture concerning Jesus: those that seem to focus on His divine-side, and those that seem to focus on His human-side. The Jehovah's Witnesses are simply ignoring, or changing, the divine-side scriptures and concentrating on those that describe His human-side.  See Hypostatic Union for information on the two natures of Jesus.

Also, God is a Trinity which means that the Father, Son, and the Holy Spirit are all divine, but are distinct persons, not three gods.  The person of the Son prayed to the person of the Father.  This makes sense since Jesus was fully divine and fully human at the same time.

If Jesus is God, why did Jesus say the Father was greater than He (John 14:28)?

He said this because His position was different than that of God the Father, not His nature.  Heb. 2:9 says that Jesus was made for a little while lower than the angels and Gal. 4:4 says, He was under the Law.  Therefore, as a man he was in a lesser position that the Father, but not different in nature.  This would also explain why he grew in wisdom and stature (Luke 2:52).

By comparison, a husband is the head of the family and the wife is not.  Though their positions are different, he has greater authority, their natures are the same.  This is how it works with Jesus.  His nature is the same as the Father, but he was sent by the Father (John 6:44) and was in a lesser position due to his incarnation and being under the Law.

Why did Jesus ask, "Why call me good, only God is good?" in Luke 18:19?

Jesus said this because it is true that only God is good.  When Jesus said this he wasn't saying that people can't do good things on a human level but that true goodness belongs to God alone.  He is the standard of what is good.  So, we must ask the Jehovah's Witness, "Was Jesus good?" Obviously, the answer has to be yes.  Therefore, when Jesus said only God was good, he was confirming His own deity because what He was doing was good.

Why did Jesus say that He could only do those things that He saw the Father do in John 5:19?

He said this because as God in flesh he was able to do the same things that God the Father could do.  No mere man or angel could rightfully say this.  If Jesus is the second person of the Trinity, then he would naturally be able to do whatever the Father can do.  Therefore, Jesus is divine.