He who believes.

[percho]

the Spirit of truth, whom the world is not able to receive, because it doth not behold him, nor know him, and ye know him, because he doth remain with you, and shall be in you. John 14:17 YLT
and when He may come -- the Spirit of truth -- He will guide you to all the truth, for He will not speak from Himself, but as many things as He will hear He will speak, and the coming things He will tell you; John 16:13 YLT

Can one be a believer, without having the Spirit of Truth?

 

[Martin Marprelate]

the Spirit of truth, whom the world is not able to receive, because it doth not behold him, nor know him, and ye know him, because he doth remain with you, and shall be in you. John 14:17 YLT
and when He may come -- the Spirit of truth -- He will guide you to all the truth, for He will not speak from Himself, but as many things as He will hear He will speak, and the coming things He will tell you; John 16:13 YLT

Can one be a believer, without having the Spirit of Truth?

Of course not (Romans 8:9). But you realise, of course, that this means that no one at all has the Spirit because the world (Gk. kosmos) cannot receive Him, and as everybody knows, 'world' means all the people in the world. :laugh:

 

[JamesL]

and when He may come -- the Spirit of truth -- He will guide you to all the truth,

Was said exclusively to the apostles, does not apply to every believer. Wrong context.

If the Spirit were to guide every believer into all truth, then anyone not having all truth would not be a believer. There would be no doctrinal disagreements among people who have all truth

If you and I disagree on even one small point, then it is a given that at least one is wrong on that small truth, and has thereby not been led into all truth, and is therefore not a believer.

 

[Reformed]

Martin referenced Romans 8:9, which reads:

However, you are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him.

There is no salvation without the Holy Spirit (a.k.a. "the spirit of truth"). The Spirit not only regenerates us, He leads us into all truth. This the helping ministry of the Spirit:

John 14:16 "I will ask the Father, and He will give you another Helper, that He may be with you forever;"

It is the Holy Spirit that allows us to appraise spiritual truth and gives us the mind of Christ:

1 Corinthians 2:15-16 But he who is spiritual appraises all things, yet he himself is appraised by no one. For who has known the mind of the Lord, that he will instruct Him? But we have the mind of Christ.