God graciously extends His invitation for all who thirst to come to His waters and receive His free gift of salvation which is offered because of the great price that Jesus paid to procure it for us (as detailed in chapter 53). It is not through the animal sacrifices (Heb. 10:4) nor the works of the Law (Rom. 3:20), but by His grace through faith (Eph. 2:8-9). Jesus declared, "If anyone thirsts, let him come to Me and drink" (John 7:37; cf. Rev. 22:17; Matt. 5:6). Many people take great pains and expense attempting to obtain satisfaction through other means, but all they find is that which "does not satisfy" (55:2; John 4:13-14; Jer. 2:13). Jesus is the only way of salvation for one's soul. He is the Living Water and the Bread of Life (John 6:35; Ps. 36:8-9). It is through His Word that one receives delight and spiritual nourishment (Matt. 4:4). Jesus is the faithful "witness" (Rev. 1:5) who brings God's message through His emissaries of the Gospel, not only to the people of Israel but to all nations. Now they will flock to join spiritual Israel (John 10:16), and in Him they will obtain "the sure mercies of David" (cf. Acts 13:34; Jer. 30:9; Ezek. 34:23-24), which are eternal life and present enjoyment of the covenant blessings.
In view of these many wonderful promises of God, Isaiah urges sinners of every nation not to delay, but respond to Jesus' invitation and seek Him while there is still time; for the time is coming when the way will be closed (John 7:34; 8:21; Prov. 1:28), and after death there will be no repentance. Isaiah beautifully expresses God's mercy and willingness to forgive those who sincerely seek Him through repentance and faith. His grace and mercy is something which surpasses human understanding (Rom. 11:33-36), and it is guaranteed by God to be active and effective through the preaching of His Word (Heb. 4:12), for His Word does not return void, and God has purposed to bring salvation (1 Pet. 1:23; 2 Cor. 9:10). Those who respond with faith and obedience to God's Word will experience His redemption, be freed from the bondage of sin and death and enter into the joy and peace of the Lord (John 5:24). Along with the rejoicing angels, all nature will share in the joy of God's grace extended to man. Have you experienced God's grace and the effectiveness of His Word in your life? May God put this thirst after Him into our lives (Ps. 42:1-2; 63:1, 5; Amos 8:11).
Although salvation is a free gift and believers are promised eternal rewards, there are still demands and responsibilities for the present time, as we read in chapters 56 and 57. The righteous who live in an ungodly world are encouraged to keep their testimony of a godly life and observe the commandments of God. The keeping of the Sabbath is emphasized. For the old covenant children of Israel, the Sabbath was a remembrance of God's power in creation and in delivering them from Egypt, as well as a covenant sign of their saving faith and commitment to God (Ex. 20:8-11; 31:13-17; Deut. 5:15). The Sabbath was to be a delight, a gift from God to His people wherein they honoured Him (Isa. 58:13). One of the main reasons for the destruction of Jerusalem and the Captivity was that the people did not keep the Sabbath (Neh. 13:15-22; Jer. 17:19-27; Ezek. 20:11-21). After the return from the Exile, the keeping of the Sabbath was the sign of the faithful remnant. For New Testament believers, however, the Old Testament observance of the Sabbath is fulfilled in following Jesus, for He fulfilled the Law, which included the Sabbath; it was but a "shadow" (Col. 2:16-17). We now are not under the Law but under grace. Therefore, the earliest Christians, still keeping the principle of the Sabbath (a day of worship and honour to the Lord in resting from normal labour), chose to observe Sunday in commemoration of Jesus' resurrection — a day that only the new creation can truly celebrate.
In the last few verses of chapter 56, and in chapter 57, Isaiah condemns the corrupt leaders, priests, and prophets of Judah who failed to take spiritual care of the people by watching and warning them when they sinned (cf. Ezek. 3:17-18). They are described by such words as blind, dumb, asleep, lazy, greedy, self-seeking, ignorant, and gluttonous drunkards. They persecuted and killed the truly righteous ones (57:1,2) and led the people astray (28:7-9; Ezek. 34; Jer. 50:6-7). Isaiah is likely describing the wicked society full of witchcraft, idolatry, and even human sacrifice (57:5) that prevailed under Manasseh towards the end of Isaiah's life (cf. 2 Kings 21:6, 9). They were guilty of harlotry in leaving God, their husband, and running after false gods. Because of these abominations, judgment was in store for them; for as the Lord says, "there is no peace for the wicked" who are like a raging sea that does not stop bring up the mire and dirt (57:20-21; 48:22; Jude 13). In His wrath God would forsake them, and their useless idols could not help them (57:13). But because of His mercy, God's wrath would not persist forever, for if that were the case, all would die (57:16; Ps. 103:9).
In the midst of his condemnation, Isaiah offers hope to the righteous, for their compassionate God will give them peace, even peace in the life hereafter (57:1-2, 13b-18). The transcendent, eternal Lord (Ps. 90:2), who is "the High and Lofty One", dwelling in "the high and holy place", condescends to live with and help those who have a "contrite and humble spirit"; they are those who fear the Lord and have repented, making Him the Lord of their lives (57:15; Ps. 34:18; 51:17; 68:4-5; John 14:16-17). God heals, guides, comforts, and gives peace to His people (26:3; Phil. 4:7; John 14:27), whether they be "far off" (Gentile converts) or "near" (Jewish converts; Eph. 2:13-14, 17).