Isaiah 43:1-2

But now thus saith the LORD that created thee, O Jacob, and he that formed thee, O Israel, Fear not: for I have redeemed thee, I have called thee by thy name; thou art mine.

But now - Notwithstanding God's past just judgments for Israel's sins.

Saith the Lord that created thee, O Jacob - not only in the general sense, but specially created as a special people unto Himself (Isaiah 43:7; Isaiah 43:15; Isaiah 43:21; Isaiah 44:2; Isaiah 44:21; Isaiah 44:24). So believers, "created in Christ Jesus" (Ephesians 2:10), "a peculiar people" - i:e., a people whom God especially chose to be His ([laos eis peripoieesin]) (1 Peter 2:9).

Fear not: for I have redeemed thee - a second argument why they should trust Him, besides creation. The Hebrew, gaa'al (H1350), means to ransom by a price paid in lieu of the captive (cf. Isaiah 43:3). Babylon was to be the ransom in this case - i:e., was to be destroyed, in order that they might be delivered: so Christ became a curse, doomed to death, that we might be redeemed.

I have called (thee) by thy name - not merely "called" in general, as in Isaiah 42:6; Isaiah 48:12; Isaiah 51:2, but designated as His own special people (cf. Isaiah 45:3; Exodus 33:12; John 10:3).

When thou passest ... through the rivers, they shall not overflow thee - so in passing Jordan, though at its "overflow," when "all the time of harvest" its "swellings" were especially dangerous (Joshua 3:15; Jeremiah 12:5).

Waters ... fire - a proverbial phrase for the extremest perils (Psalms 66:12; also Psalms 138:7). Literally fulfilled at the Red Sea (Exodus 14:1); and in the case of the three youths cast into the fiery furnace for conscience' sake (Dan Red Sea (Exodus 14:1); and in the case of the three youths cast into the fiery furnace for conscience' sake (Daniel 3:25; Daniel 3:27).