Even though Joshua's "retirement speech" to the Israelites is most certainly not the same thing we do when we "share Jesus" with people, there are a lot of things we can learn from it about how we should share Jesus when we do.
I say it's not the same thing, of course, because Joshua was a Jew who lived many hundreds of years before Jesus. He was not a Christian, because at that time there were no such people. But he was a devout follower of God, which is not too different from what Christians are supposed to try to be. And that's where some of the similarities can show up.
First off, he clearly says that the Israelites will need to choose whom they serve. They must make a free choice about their allegiance. God will not coerce them into serving him. He won't trick them into following him. He won't throw a bolt of lightning at their feet and then say, "Next one's coming faster." They will either follow him or not, but they are free to choose for themselves which one of those paths seems best to them.
That means they have to make an informed choice. Joshua won't have them choose from ignorance, which is one reason why he gives a brief overview of their history as a people since the time of Abraham. They will need to know what God has done for them and how difficult a choice they may be making, so that their choice is truly a free one.
When we talk about what it means to follow Jesus, we need to do the same thing. We need to tell people the truth about what that means. Some parts of it are good, but some parts of it are hard. If we make up stuff that sounds good but isn't true, we run the risk of people deciding to follow Jesus based on lies and then turning away from him when they find out the lies. All kinds of people would follow Jesus if we told them that they would get a promotion, a raise, kids that never lip off and hair that never falls out or chocolate that has no calories -- depending on their gender.
None of those things would be true, though, so the first time the bathroom light glare from his head makes a fellow squint or the first time a lady realizes that chocolate cake really does have calories they're outta here.
The temptation might be to say nothing about Jesus at all becaise we don't know what we should say or don't know enough about church history or the Bible. But that doesn't work. God wants us to make an informed choice, which means we need information. God doesn't operate on a "Hey, I just met you/This is crazy" basis. And that means we need to learn a little bit. Not everything. If someone asks us about the hypostatic union of the divine and human in Christ, we're still free to say, "Gesundheit." But we need to know something about Jesus's message of how our relationship with God is broken, but God's grace in Jesus heals it.
And Joshua is clear that whether the Israelites serve the Lord or the gods of some other nation, they will serve somebody (and I have now quoted Raylan Givens, Carly Rae Jepson and Bob Dylan, making this one of the weirdest sermons ever). In his day and time, people who believed in no divine presence whatsoever were few and far between. Some cultures added everyone else's gods into their mix in order to make sure all the heavenly bases were covered. Some maintained only their own gods. But there were not many who would match our modern definition of an atheist.
The same question faces us. Will we serve the Lord, or will we serve other gods? Our "other gods" may have different names than Moloch or Asherah -- like power, or wealth, or fame. But they tempt us away from the Lord just as well as those ancient idols did.
Even one of those people who completely rejects the idea of anything other than this material world chooses to "worship" something -- themselves, if nothing else. When they say they and they alone decide what they will do, then they make themselves gods. And if you think all of your decisions will come from your own free will, see how long you can hold your breath.
When we share the gospel message with people, we share with them two hard-cased truths of life: In this life, you will serve somebody. And there is no better One to serve than the One who made us, redeemed us, and showed in the person of his son that he would rather die than live without us.