A:  From The Urantia Book:

The keys of the kingdom of heaven are: sincerity, more sincerity, and more sincerity. All men have these keys. Men use them–advance in spirit status–by decisions, by more decisions, and by more decisions. The highest moral choice is the choice of the highest possible value, and always–in any sphere, in all of them–this is to choose to do the will of God. (39:4.14) “