It is vitally important to consider the difference between "to" and "on". For example, we are all aware of the following:
"Peace on earth, goodwill to men".
But then there is the following:
"Do not think that I have come to bring peace to the earth. I have not come to bring peace, but a sword." - Matthew 10:34
Are these contradictory? No, not at all. This plays off of that famous old phrase - Christians are to be in the world, but not of the world. There is peace on earth - but not peace to this fallen place. Indeed, the fallen world will never stop fighting the Gospel - and thus between Christians and the world there will always be struggle. We will all preach the Law, and the world will always reject it. We will preach the Gospel, and the world will always disdain it.
The difference between to and on. A vital difference that describes our whole lives.