Short answer
– The most likely author of Jeremiah 17:7–8, from a mainstream evangelical perspective, is the prophet Jeremiah himself (with his secretary/scribe Baruch ben Neriah involved in recording and compiling his oracles).

Who Jeremiah is (evangelical summary)
– Jeremiah was a prophet called by God in Judah in the late 7th / early 6th century BCE (active roughly c. 627–585 BC).
– He was from Anathoth and was of priestly descent (Jer 1:1–3; 1:6).
– Evangelicals often call him the “weeping prophet” because of his laments over Judah’s sin, the coming judgment, and the suffering he endured for proclaiming God’s word.

Why Jeremiah is regarded as the author of the verse
– The book bears his name and repeatedly identifies the speaker as Jeremiah (many first-person oracles and autobiographical notes).
– Jeremiah 17:7–8 appears as part of his prophetic ministry—its style and themes (trust in the LORD, judgment for covenant unfaithfulness, and pastoral imagery) fit Jeremiah’s message.
– Conservative scholars acknowledge that Jeremiah dictated much of his prophecy to a scribe, Baruch (Jer 36:4–32). Baruch likely wrote and helped preserve Jeremiah’s oracles but did so as Jeremiah’s authorized secretary, not as the principal originator of the material.

Dating and textual considerations
– The material in Jeremiah comes from the period leading up to and including the Babylonian threat and exile. Jeremiah addressed both impending judgment and the need to trust God rather than human or political alliances.
– Evangelicals typically accept the Masoretic Text as the reliable Hebrew basis (though they also note the Septuagint and Dead Sea Scrolls for textual comparison). Differences in order and some content between Hebrew and Greek witnesses are understood as editorial or transmission phenomena that do not negate Jeremiah’s prophetic authorship.

Theological significance (evangelical emphasis)
– Jeremiah 17:7–8 contrasts trust in the Lord with trusting in man or things; it promises spiritual flourishing for those who place their confidence in God.
– Evangelicals emphasize the verse’s covenantal context: trusting the covenant God brings life and blessing, while covenant unfaithfulness brings judgment.
– It points forward to deeper New Testament themes of faith and dependence on God through Christ, and it is used pastorally to encourage personal trust in God amid trials.

Practical application (how evangelicals tend to use it)
– Used in preaching and devotional life to encourage reliance on God in crisis, in prayer, and in moral decision-making.
– Commonly applied to personal discipleship: Christians are urged to be “like a tree planted by water” — rooted in the living God, sustained by his Spirit and Word.

Suggested further reading (evangelical-friendly)
– A conservative commentary on Jeremiah (for example, those in the NIVAC, EBC, or NICOT/NICNT series written from evangelical scholars).
– Study Bibles popular in evangelical circles (ESV Study Bible, NIV Study Bible) for notes on authorship, dating, and historical background.

If you want, I can:
– Provide a brief life sketch of Jeremiah with key dates and events,
– Show several evangelical commentaries’ takes on the authorship and composition of Jeremiah,
– Or give a short sermon-style application of Jeremiah 17:7–8. Which would you prefer?