For the most part, two things get redeemed these days: coupons and yourself. You redeem a coupon when you buy 2 low-sodium single-serving ManChow prepared dinners, any flavor. You redeem yourself when you win the championship you didn't win last year.
Given that, yesterday's Psalm refrain --
With the Lord there is mercy and fullness of redemption.
-- might not sound like much more than the formulaic cheering for God freethinkers dismiss Christian worship as. (Though there's more of the formulaic than of the cheering during the Responsorial Psalm at most of the Masses I've attended.)
But the redemption the fullness of which is with God is worth more than $2, or even a trophy. It's a redemption in the old sense of a ransom. God ransoms His people from their slavery.
The statement, "God redeems His people from slavery," neatly summarizes the plot of Scripture; TV listings could use it to describe "Bible: The Movie." But the statement also contains a highway's worth of stumbling blocks.
If you don't think you're enslaved, then you won't care much whether someone redeems you. The slavery from which God redeems His people is slavery to sin and death, but plenty of people are more than willing to accept death as long as they're free to sin. The fleshpots of Egypt have always been an easy sell.
Moreover, if you're redeemed from something, you must be redeemed to something else. If you're blinded by sin, the freedom of the children of God may look just like another form of slavery. Better the devil you know than the God you don't know.
On top of that, the transition from slavery to freedom doesn't happen through Divine fiat. Its cause is an act of redemption, an act of ransom, about as ugly and bloody an act as you can have. If that's not bad enough, God expects His children to act just like Him, to fill up in their flesh what is lacking in the afflictions of Christ. God even thinks it redounds to His glory if He cools His heels while those He loves suffer and die, then uses that suffering and death of others as the means to His own end. Who wants to get mixed up in all that?
The Christian evangelist, which is to say the Christian, must be prepared to guide others past these scandalous parts of the Gospel. He must be able to show how slavery leads to sorrow even when it seems pleasant, how freedom leads to joy even when it seems noxious, how redemption done for the sake of love must be done completely and without reservation or it's not true redemption. And of course, to be able to show that these things are true, he must know them to be true in his own heart.