Short answer: Most evangelicals identify the Apostle Paul as the author of 2 Corinthians 1:3–4.

Why evangelicals say Paul wrote it
– The letter itself names Paul (2 Cor. 1:1) and is written in Paul’s unmistakable personal, pastoral style.
– Early church tradition attributes 2 Corinthians to Paul, and the internal claims (autobiographical details, apostolic defense) fit what we know of Paul.
– Conservative and evangelical scholarship generally accepts Pauline authorship and dates the letter to the mid‑50s AD (after 1 Corinthians), written from Macedonia during his third missionary period.

Who Paul was (brief)
– A Jewish Pharisee and Roman citizen (Acts 22, Philippians 3).
– Former persecutor of the church who was converted on the Damascus road (Acts 9).
– Trained under Gamaliel, became a missionary apostle to the Gentiles.
– Founded many churches, wrote a number of New Testament letters (thirteen traditionally attributed to him).
– Known for theology emphasizing justification by faith, the death and resurrection of Christ, life in the Spirit, and the meaning of Christian suffering and ministry.

Context of 2 Corinthians 1:3–4
– 2 Corinthians is highly personal and pastoral: Paul defends his apostolic authority, explains his travel plans, asks for reconciliation with the Corinthian church, and discusses the collection for Jerusalem.
– Paul had experienced opposition, hardship, and a “painful visit” and “severe letter” earlier (see chapters 1–2). The opening verses set the tone by praising God and introducing the theme of comfort in suffering.

Short exegesis of 2 Corinthians 1:3–4 (what it says and means in evangelical terms)
– The verse: Paul calls God “the Father of mercies and God of all comfort” and says God “comforts us in all our affliction, so that we may be able to comfort those who are in any affliction.”
– Theologically: It stresses God as the primary source of compassionate care (the Father who mercies) and the one who provides comfort (Greek paraklēsis — comfort/encouragement). It also implies a Trinitarian awareness (“God and Father of our Lord Jesus Christ”) common to evangelical reading.
– Pastoral emphasis: God’s comfort is not merely for private relief but is given so believers can minister that same comfort to others. Suffering has purpose: through it God equips and commissions Christians for compassionate ministry.
– Application (evangelical): Christians can trust God in trials, receive His comfort, and be used to comfort and encourage others — this is part of the life and mission of the church.

Practical note on Paul’s credibility
– Paul’s own experiences of suffering (detailed elsewhere in Scripture) give his statements about comfort weight and authenticity. Evangelicals emphasize both his apostolic authority and his pastoral heart — he writes as a suffering servant who knows God’s sustaining comfort.

If you’d like, I can:
– Give a short devotional application based on these verses, or
– Summarize how different Bible translations render the passage, or
– Provide references to a few conservative commentaries and study Bible notes that treat 2 Corinthians from an evangelical perspective.