It is either the heart of wisdom or evil that takes it seriously.
When someone says, "I trust you," we might think that the action implied is on the part of the one who expresses the trust. Not so. The trust of another person says to me, I must now be even more than I was before the statement was made. It's easy to say that trust is earned, but beyond that is where things become remarkable; when trust is kept.
The foolish person tosses trust in the direction of everyone who is kind to them. Or someone they wish to be friends with. Or simply because the person wears a title that seems to encompass trust like pastor, wife, friend, brother, sister, parent. The foolish person who receives trust and treats it as though it were bullet-proof replaces the sacred with the arrogant. As soon as we are trusted, we are changed into something more than we are and must now lean toward earning such an honor.
The evil person (although no one is ever truly evil are they? smirk.), takes trust and uses it like a thief uses a door left open when homeowners are away. They must trust that this is a safe neighborhood to leave their door open. And so evil says that the one who drops his guard deserves whatever they get. The action of trust is thrown back on the person who trusted and any consequence is theirs.
The wise person, however, lives with integrity and receives trust as the natural response to their lives. And when this wise person is told, "I trust you," something in them raises the standard even higher. Now that I have earned your trust, it is a greater responsibility to keep it.
The foolish person receives trust lightly and thinks it cannot be lost.
This is why the world cannot see Christ. The essence of knowing him is trust in this Savior who cannot be seen, heard or touched. We much teach trust by earning it and keeping it. From human trust the road is not so far to faith.