Pro nobis. Pro vobis.*
This alone can show how desperate God is to embrace even the worst of us.
Here are the Law and the Gospel in all their fullness, reduced to a single image. Christmas and Easter may be more pleasant. But Jesus came for Good Friday. See this for a discussion of why today is the most important day in the Church Year. And here is a sermon I preached at St. Mary's on Good Friday several years ago.
But no sermon could ever be as effective as the sight of God hanging in bloody tatters to clean up our moral messes, so that we could be His children.
You can keep your nice, sterile, pleasant empty crosses. It's the One Who is hanging from the cross that saves us.
*"For us. For you."