Well one reason is because the resurrection of Jesus Christ second reason because we have an inheritance that is Incorruptible and undefiled and that fadeth not away reserved in heaven and the third is because we are kept by the power of God through faith unto salvation ready to be revealed in the last time when Jesus come back
Before humans it was B.C now it is A.D
I believe through conquest and colonization
1) he helped us go through the Great Depression without him there would have been chaos
2) he helped us win WW2 and kept many Americans morale up
3) he didn't just talk, he acted on what he said
these all made him become one of the great presidents