I hear from God from His word (chiefly), but I know I have heard from Him when I can clearly see the black, horrid darkness of my own sinful heart. It always compels me back to Christ first for mercy, and then for further sanctification.

Evidence, Hisalone, is what Pilgrim is talking about. Perceptible, enduring proof, visible to us and to others, that we belong to God. Not just in the things we say, but in all our deeds, our reactions to injustice, to trial, to hardship, triumph, abundance, poverty, suffering, and comfort.

Yes, the law is indeed written our our hearts, but our hearts and consciences are impure and conflicted. The only reliable and pure way even the very elect have to know God's law is through the infallible and eternal written word! How can we obey God if we don't know what He commands? Without His word, we rely upon whatever "inward" perceptions (tainted by our ever-present fallen nature and finite, fallible interpretation of it) we can conjure up, and upon our own inventions that we suppose will please God.

That is superstition, not obedience!