When Jesus said
"He will guide you into all the truth" it was not a promise to all believers. He was personally addressing the 11 disciples when he was preparing them for Pentecost. It was part of the same discourse where he said...
"But now I am going to Him who sent Me; and none of you asks Me, ‘Where are You going?’ But because I have said these things to you, sorrow has filled your heart. But I tell you the truth, it is to your advantage that I go away; for if I do not go away, the Helper will not come to you; but if I go, I will send Him to you...But when He, the Spirit of truth, comes, He will guide you into all the truth; for He will not speak on His own initiative, but whatever He hears, He will speak; and He will disclose to you what is to come."
The "you" in this passage is the disciples. The Holy Spirit would guide them into all truth as they taught and wrote the New Testament.
It is plainly obvious that the Holy Spirit does not internally guide today's believers into all truth because if he did we would all agree with each other! (unless we claim that those who disagree with our particular set of doctrines are not Christians!)