One cannot understand even the simplest of truth unless enlightened through the scriptures and by the Holy Spirit. Everything argument is distortion. And we must guard against the hardness of our own hearts. For the evidence that we believe may be heresy.
The early church fathers rightfully understood that there is only one source of truth-the scriptures. As Cyprian stated the Old and NT were “fountains of divine fullness from which the Christian must draw strength and wisdom.”
Since you paint them with a broad brush, you ought to be able to present lots of in-context citations backing up this remarkable claim.
But really ... the only source of truth??
So God himself is demoted, and is not a source of truth?
So the church founded by God, which St Paul calls directly, "the pillar and ground of the truth," is not a source of truth?
So creation, which Scripture teaches in several places testifies to God's glory and his law, so that even the Gentiles are "without excuse," is not a source of truth?
Man's right reason, created by God to glorify him, is not a source of truth?
I'm pretty sure that none of the early fathers embraced a notion so manifestly false and contrary to Scripture.