The God Who Testifies about Himself in Creation, Providence, and Redemption

God testifies about Himself by His works of common grace in the whole world and special grace among believers.

1. God testifies about Himself in "common grace."
   1.a. All the good that He does to all His creatures (creation and providence)
   1.b. Rain from heaven, fruitful seasons
   1.c. Physical neediness and fulfillment
   1.d. Spiritual neediness and fulfillment
2. God testifies about Himself in "special grace" of conversion
   2.a. God doesn't owe anyone (v16) to turn us from useless things (v15). The preaching of repentance is a great mercy from God.
   2.b. The giving of faith is a great mercy from God (cf. 13:48)
   2.c. Signs like in v8–10 affirmed the preaching and the faith (cf. 14:3; 2:43; 2Cor 12:11–12; Heb 2:3–4). This was also true in Jesus's own ministry (cf. Mt 9:2–8; Mk 2:5–12; Lk 5:20–26; cp. Mt 13:57–58, Mk 6:4–6)
3. God testifies to this "special grace" especially in sanctification
   3.a. 13:52 more likely referring to fruit of the Spirit than signs of an apostle
   3.b. vv19–20 are also "signs of an apostle" in the marvelous sanctification of Paul! (cf. 1Cor 4:9–16; 2Cor 12:12 vs 12:9–10)