People should be viewed as ends in themselves, not merely means to ends. If they are viewed as means to ends, this is another way of stating that they are viewed as objects. When we view other people as objects, instead of viewing them as people made in the image of God, we not only de-value them, but further the delusion that we are really the only people who matter—and that other people are valued instrumentally only insofar as they serve our purposes. This, in turn, gives us a warped view of God, where he only values us instrumentally.
Here is a concrete way that can work out: Men often view women as sexual objects, there to serve them and bring them pleasure. Often, people in society work to overcome the misogynistic behavior associated with this. Christians, specifically, seek to commit to one woman, in marriage before God, for as long as they are alive together. The issue is that, too often, it is only the behavior that is modified. Often, unexamined assumptions are left unchecked, and the prevailing attitude is barely affected, if at all. Thus, for the Christian man, women are still objects to be used—but I only am allowed to use one, namely, my wife.
This is not viewing people as made in the image of God. Instead, we should strive every day to view not only women, but all people in the image of God, and recognize they are not objects to be used. The same thing can happen with women to men (in terms of love, stability, relationship status, money), with co-workers, and so on. So long as you view people implicitly as furtherances to your pleasure, you have failed. It’s why people treat each other so badly on the internet—it’s easier to objectify them when you can’t see them. Let’s try seeing people as God does: as ends in themselves, people made in the image of God, for whom Christ died.