Jesus taught us to love one another. This has led to some Christian people achieving great things.
Prison reform in Victorian times was led by Christians eg Elizabeth Fry.
The movement to end slavery ( Wilberforce)
Sunday schools which led to education for all.
Many of the children's charities like Barnado's and Action for Children were started by Christians.
The trades unions had their roots in the Christian non conformist movement.
Democracy itself stemmed from Christian thought and ideals.
What about Arthur Guinness who founded the Guinness Brewing Co. in 1755. He learned the art of brewing from his father and succeeded in establising a flourishing company. Arthur, a committed Christian, used his influence and wealth to help others.
Douglass Macmillan who founded the cancer charity was a Christian.
I could go on.
I don't think that the Gideons are going to do too much harm by giving out their New Testaments, and if even a few kids who read bits of it decide to put something back into society for other people, it will be well worth it.