So Jesus, when he spoke to Moses and Elijah at the Transfiguration, was either sinning or just setting a really, really bad example for us?
In fact, if someone appears to you as Moses or Elijah, you might want to check their IDs (i.e., "test their spirits").
Jesus also spoke to a dead Lazarus ("Lazarus, Come Forth"), but I don't think that meant that we are supposed to pray to dead people.
Nice pope ya got there!
Put the verse and your question in context.
1Six days later Jesus took with Him Peter and James and John his brother, and led them up on a high mountain by themselves. 2And He was transfigured before them; and His face shone like the sun, and His garments became as white as light. 3And behold, Moses and Elijah appeared to them, talking with Him. 4Peter said to Jesus, “Lord, it is good for us to be here; if You wish, I will make three tabernacles here, one for You, and one for Moses, and one for Elijah.” 5While he was still speaking, a bright cloud overshadowed them, and behold, a voice out of the cloud said, “This is My beloved Son, with whom I am well-pleased; listen to Him!” 6When the disciples heard this, they fell face down to the ground and were terrified. 7And Jesus came to them and touched them and said, “Get up, and do not be afraid.” 8And lifting up their eyes, they saw no one except Jesus Himself alone. Matt 17:1-8 NASB 95
Note what did and what did not happen.
That Moses and Elijah appeared indicates they were not in Purgatory.
It does indicate there is an afterlife.
But pay special attention to Peter in this passage. He asked to build three tabernacles...one for Jesus, Moses and Elijah.
Jesus did not respond to his statement. What can we draw from this?
No tabernacles or shrines are to be built to people. This would eliminate all of the so called Marian shrines around the world built to honor/worship Mary.