If we are to cherish freedom, and to guard it, we must remember what the alternative is: the bread of affliction and the bitter herbs of slavery. - Jonathan Sacks

The meaning of the word "true" here is similar to the word Amen said after a blessing. It is an act of affirmation and ratification, reminding us that the Shema is less a prayer than a declaration of faith.

[T]oday there is hardly a country in the world, certainly not a single country in Europe, where Jews feel safe.
A society, or for that matter, a political party, that tolerates antisemitism, that tolerates any hate, has forfeited all moral credibility.

The first of the "request" prayers in the daily Amidah is a fractal. It replicates in miniature the structure of the Amidah as a whole.