The faithfulness of our triune God is one of the most comforting, faith-strengthening, and amazing teachings of Scripture. It ties in with the promises of God in the covenant of grace, Christ’s work on the cross, the preservation of the saints, and many more biblical truths. Edward Leigh (17th C.) and Louis Berkhof (20th C.) are two of the many Reformed teachers who understood the beauty of God’s faithfulness.
“[The] faithfulness of God is of the utmost practical significance to the people of God. It is the ground of their confidence, the foundation of their hope, and the cause of their rejoicing. It saves them from the despair to which their own unfaithfulness might easily lead, gives them courage to carry on in spite of their failures, and fills their hearts with joyful anticipations, even when they are deeply conscious of the fact that they have forfeited all the blessings of God” (Berkhof, Systematic Theology, II.71).
“God’s faithfulness is the ground of all true religion. … 1) We must ground all doctrine of faith, all the articles of faith, all our judgment and opinion in matters of faith, upon this faithfulness of God, and this by holding fast all the faithful word (Titus 1:9, Rom 3:4). 2) All our obedience must be grounded on this [faithfulness of God] (John 3:33, Heb 11:11). 3) All our prayers of faith must be grounded on God’s faithfulness (Dan 9:16, 1 John 1:9, 1 Pet 4:19, 31, Ps 1:5). 4) All sound profession of faith must be grounded on this [faithfulness of God] (Gen 17:1, Ps 91:4). 5) All true perseverance of the faith [must be grounded in the faithfulness of God] (1 Cor 1:8, 10:13, Ps 91:4)” (Leigh, found in PRRD vol 4).
We can summarize like this: because God’s great and abounding covenant faithfulness reaches to the clouds and endures forever, his people can confidently and joyfully find certain and eternal refuge in him, through Christ, even when and though they stumble. Or, in Paul’s words, now may the God of peace himself sanctify you completely, and may your whole spirit and soul and body be kept blameless at the coming of our Lord Jesus Christ. He who calls you is faithful; he will surely do it (1 Thes. 5:23-24). And so the Canons of Dort rightly state that the perseverance of the saints is based ultimately on God’s faithfulness. “God is faithful, who, having conferred grace, mercifully confirms and powerfully preserves them [the elect] therein, even to the end” (CoD 5.3).
Don’t let anyone ever tell you that doctrine is dry, boring, and “unrelatable” to the everyday Christian life!