2 Cents

In Jude v. 5 we read this:

Now I want to remind you, although you once fully knew it, that Jesus, who saved a people out of the land of Egypt, afterward destroyed those who did not believe. (ESV)

Notice anything strange about that verse?

It's the word "Jesus".  Typically seeing "Jesus" in a Bible verse is something we would completely expect.

But not when we're talking about Jesus delivering the Israelites out of the hands of Pharaoh via Moses and the 10 Plagues in the exodus.  That's what Jude is referring to here.

Now it's important to note there are some disagreements as to whether the verse should read "Jesus, who saved," or "the Lord, who saved."

The newest addition of the standard Greek New Testament (Nestle-Aland), the NA28, has the Greek word for "Jesus" here instead of the Greek word for "Lord."  However, the previous edition, the NA27 actually had "Lord."  Bill Mounce, renowned NT Greek scholar, chronicled the change here.

Suffice it to say there is very good reason to translate this verse "Jesus" as is evident by the extremely reliable and accurate ESV committee translating it that way.  (For more support for this translation read this short article)

Some argue that the latter would make more sense because why would Jude speak of Jesus doing things in the book of Exodus?

But consider this.  It's not unprecedented for the NT authors to mention Jesus as being active in the OT.  For instance, 1 Corinthians 10:3-4, speaking of the Israelites shortly after the exodus from Egypt, says...

all were baptized into Moses in the cloud and in the sea, and all drank the same spiritual drink.  For they drank from the spiritual Rock that followed them, and the Rock was Christ.

So it's most certainly not a stretch to say that Paul (the author of 1 Corinthians) and Jude were both on the same page here (which by the way is a strong argument for these men being inspired by God when they wrote!).  If Jesus was helping out the Israelites after the exodus, certainly we would expect him to be helping them during it!

Finally, let's allow the Apostle John to clear this all up for us:

In the beginning was the Word, and the Word was with God, and the Word was God.  He was in the beginning with God.  All things were made through him, and without him was not any thing made that was made.

If you follow the passage in John 1 you'll see clearly that this "Word" John's talking about is Jesus.

So in other words, Jesus has always existed with God.  Even the creation of the universe was done through Jesus Christ.  So of course Jesus was working all throughout the Old Testament, including the exodus of the Israelites from Egypt as mentioned in Jude 5.

Jesus is all over the Bible.  In fact, the entire book is about him.