The Heidelberg Catechism: Lord's Day 17
45. Question: How does Christ's resurrection benefit us?
Answer: First, by His resurrection He has overcome death, so that He could make us share in the righteousness which He had obtained for us by His death. Second, by His power we too are raised up to a new life. Third, Christ's resurrection is to us a sure pledge of our glorious resurrection.
 Rom. 4:25; I Cor. 15:16-20; I Pet. 1:3-5.  Rom. 6:5-11; Eph. 2:4-6; Col. 3:1-4.  Rom. 8:11; I Cor. 15:12-23; Phil. 3:20, 21.
The Heidelberg Catechism: Lord's Day 8
24. Question: How are these articles divided?
Answer: Into three parts: the first is about God the Father and our creation; the second about God the Son and our redemption; the third about God the Holy Spirit and our sanctification.
25. Question: Since there is only one God, why do you speak of three persons, Father, Son, and Holy Spirit?
Answer: Because God has so revealed Himself in His Word that these three distinct persons are the one, true, eternal God.
 Deut. 6:4; Is. 44:6; 45:5; I Cor. 8:4, 6.  Gen. 1:2, 3; Is. 61:1; 63:8-10; Matt. 3:16, 17; 28:18, 19; Luke 4:18; John 14:26; 15:26; II Cor. 13:14; Gal. 4:6; Tit. 3:5, 6.