Why did St. Paul write the fourteenth chapter of I Corinthians, then? Shouldn’t the Spirit interpret, then? Or did St. Paul err in preaching that prophesy independent of Scriptures was profitable?
Where did anyone in Scripture claim that all members of the Church would be infallible in their interpretations?
I Cor 12:7-11
“To each individual the manifestation of the Spirit is given for some benefit. To one is given through the Spirit the expression of wisdom; to another the expression of knowledge according to the same Spirit; to another faith by the same Spirit; to another gifts of healing by the one Spirit; to another mighty deeds; to another prophecy; to another discernment of spirits; to another varieties of tongues; to another interpretation of tongues. But one and the same Spirit produces all of these, distributing them individually to each person as He wishes.”
And, of course, the inevitable verses 27-31 of same:
“Now you are Christ’s body, and individually parts of it. Some people God has designated in the church to be, first, apostles; second, prophets; third, teachers; then, mighty deeds; then, gifts of healing, assistance, administration, and varieties of tongues. Are all apostles? Are all prophets? Are all teachers? Do all work mighty deeds? Do all have gifts of healing? Do all speak in tongues? Do all interpret? Strive eagerly for the greatest spiritual gifts. But I shall show you a still more excellent way.”
The only "infallibility" required for salvation is that of Jesus Christ.
No church on earth has everything 100% correct, and men still die sinning. By the grace of God, if that man is a member of Christ's flock, those sins have been covered by His one-time, perfect, accomplished sacrifice on the cross.