Albert Barnes Commentary Luke 24:38

"And he said unto them, Why are ye troubled? and wherefore do questionings arise in your heart?" — Luke 24:38 (ASV)

Why are you troubled? Why are you alarmed or frightened?

And why do thoughts... The word thoughts here means doubts or suspicions. It is used in this sense also in 1 Timothy 2:8. The doubts which they had were whether he was the Christ. He reproves them for doubting this, for:

1. The Scriptures had foretold his death.
2. He had himself repeatedly done it.
3. They had now the testimony of Peter that he had seen Jesus alive, and of the angels that he was risen.

After all this evidence, Jesus reproves them for doubting whether he was truly the Messiah.