While some think that Thomas deserves a hallowed place next to the New Testament (NT) Gospels of Matthew, Mark, Luke, and John, there's an essential difference that separates the two.
That difference is evident when you compare the familiar story of Peter's great confession in the Gospels (found in Matthew 16:13-20, Mark 8:27-30, and Luke 9:18-27) with the version given by the Gospel of Thomas.
Matthew 16:13-20 tells us:
13 When Jesus came to the region of Caesarea Philippi, he asked his disciples, "Who do people say the Son of Man is?"Now compare that story with saying # 13 in the Gospel of Thomas:
14 They replied, "Some say John the Baptist; others say Elijah; and still others, Jeremiah or one of the prophets."
15 "But what about you?" he asked. "Who do you say I am?"
16 Simon Peter answered, "You are the Christ, the Son of the living God."
17 Jesus replied, "Blessed are you, Simon son of Jonah, for this was not revealed to you by man, but by my Father in heaven. 18 And I tell you that you are Peter, and on this rock I will build my church, and the gates of Hades will not overcome it. 19 I will give you the keys of the kingdom of heaven; whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven." 20 Then he warned his disciples not to tell anyone that he was the Christ.
While the New Testament Gospels reveals Jesus' identity--He is the Christ, God's Chosen One, Israel's Messiah--the Gospel of Thomas keeps it under wraps. In fact, if Thomas tells what he knows, the disciples will face harsh judgment! And even though Jesus in the NT tells his disciples "not to tell anyone" he is the Christ, you as the reader have been given the inside scoop; you know who He is.
Jesus said to his disciples, "Compare me to something and tell me what I am like."
Simon Peter said to him, "You are like a just messenger."
Matthew said to him, "You are like a wise philosopher."
Thomas said to him, "Teacher, my mouth is utterly unable to say what you are like."
Jesus said, "I am not your teacher. Because you have drunk, you have become intoxicated from the bubbling spring that I have tended."
And he took him, and withdrew, and spoke three sayings to him. When Thomas came back to his friends they asked him, "What did Jesus say to you?"
Thomas said to them, "If I tell you one of the sayings he spoke to me, you will pick up rocks and stone me, and fire will come from the rocks and devour you."
The difference is even more evident. In the Gospel of Thomas, we just saw that Jesus pulls aside the privileged disciple and tells him something that neither the other disciples, nor we as readers, are permitted to hear. Compare that with the New Testament's Matthew 17:1-9, Mark 9:2-13, and Luke 9:28-36, when Jesus leaves the 12 and takes along only Peter, James, and John. Here's Matthew's account:
1 After six days Jesus took with him Peter, James and John the brother of James, and led them up a high mountain by themselves. 2 There he was transfigured before them. His face shone like the sun, and his clothes became as white as the light. 3 Just then there appeared before them Moses and Elijah, talking with Jesus.
4 Peter said to Jesus, "Lord, it is good for us to be here. If you wish, I will put up three shelters—one for you, one for Moses and one for Elijah."
5 While he was still speaking, a bright cloud enveloped them, and a voice from the cloud said, "This is my Son, whom I love; with him I am well pleased. Listen to him!"
6 When the disciples heard this, they fell face down to the ground, terrified. 7But Jesus came and touched them. "Get up," he said. "Don't be afraid." 8 When they looked up, they saw no one except Jesus.
9 As they were coming down the mountain, Jesus instructed them, "Don't tell anyone what you have seen, until the Son of Man has been raised from the dead."
Once again in the New Testament, when Jesus pulls aside a few disciples and reveals something that's not told to the rest of the group, we as readers are privileged to be given insight into the person of Jesus. You don't get that kind of revealing information in the Gospel of Thomas.
In the end, the Gospel of Thomas and the New Testament Gospels offer two competing views of spirituality.
With Thomas, you get Jesus' secret sayings, but even Jesus doesn't give you much help in figuring out its meaning. That's left to you.
But with the NT Gospels, Jesus tells you who He is and makes plain the response He desires from us--repentance, faith, and obedience.