The chosen nation enjoyed its greatest successes, both physical and spiritual, under Joshua and under David and Solomon. Faith was evident, and frequently described, but seldom in the terms we use, such as “faith,” “belief” and “trust.” Instead the key for success was expressed in these terms:
[Be] careful to do according to all the law that Moses My servant commanded you. Do not turn from it to the right hand or to the left, that you may have good success wherever you go. This Book of the Law shall not depart from your mouth, but you shall meditate on it day and night, so that you may be careful to do according to all that is written in it. For then you will make your way prosperous, and then you will have good success (Joshua 1:7-8).
Keep the charge of the LORD your God, walking in His ways and keeping His statutes, His commandments, His rules, and His testimonies, as it is written in the Law of Moses, that you may prosper in all that you do and wherever you turn (1 Kings 2:3).
David was near death when he spoke to Solomon in 1 Kings 2. He had already penned Psalm 32, which Paul quotes to prove that David rejoiced in salvation he could never earn.
David also speaks of the blessing of the one to whom God counts righteousness apart from works: “Blessed are those whose lawless deeds are forgiven, and whose sins are covered; blessed is the man against whom the Lord will not count his sin” (Romans 4:6-8).
David depended fully on God’s grace. Therefore, David’s charge to walk in God’s ways and rules was not legalistic. It was, under that covenant, the way to express trust in God.
Old Testament charges to obey God were not legalistic.
The charge of Joshua 1:7-8 came directly from the Lord. Was God promoting human self-reliance? Rather, He was promoting faith, saying in effect, “Trust My way rather than yours, and you will succeed.” Joshua did that carefully and taught it to others (Joshua 4:10; 8:30-35; 23:6; 24:15-24). Joshua “left nothing undone of all that the LORD had commanded Moses” (Joshua 11:15 cf. Numbers 14:24; 32:11-12; Deuteronomy 1:36).
Scripture testifies that “the LORD was with Joshua” (Joshua 6:27). Joshua’s conquest of Jericho was “by faith” (Hebrews 11:30). Joshua was no legalist. His wholehearted obedience was genuine faith. Likewise, every hero of faith described by Hebrew 11 had a faith that was both passive (in accepting God’s promise) and active (in humbly complying with God’s will). These principles continue throughout the Old Testament, as epitomized by Hezekiah’s active trust.
He trusted in the LORD, the God of Israel, so that there was none like him among all the kings of Judah after him, nor among those who were before him. For he held fast to the LORD. He did not depart from following Him, but kept the commandments that the LORD commanded Moses (2 Kings 18:5-6).