Question: Was Judas a believer? Did he lose his salvation?
Answer: Judas was never a believer and therefore never saved. Jesus addressed a group that was following Him and said, "'But there are some of you who do not believe.' For Jesus knew from the beginning who they were who did not believe, and who it was that would betray Him." (John 6:64).
Then, addressing the 12 disciples Jesus said, "'Did I Myself not choose you, the twelve, and yet one of you is a devil?' Now He meant Judas the son of Simon Iscariot, for he, one of the twelve, was going to betray Him" (John 6:70-71).
Jesus knew He had to go to the cross and chose Judas as a disciple because He knew that he would betray Him.