The heart of Buddhist training, and its brilliant effectiveness, lies in the use of Upaya, or skillful means. The Buddha gave many teachings in his day to many people of different levels of ability to comprehend and put into practice his teachings. Instead of presenting set "lectures," the Buddha taught each person according to his means. Some people's mental disposition and past experiences allow them to understand and improve their practice through direct Wisdom teachings--to these people the Buddha taught at an "advanced" level, framing the teachings in terms of emptiness and our inherent Buddha-nature. For others, such an approach would leave them behind, unable to improve their, and others', lives through the Buddha's teachings. To these people, the Buddha taught in a more directly practical manner. For example, to those whose dispositions were such that they could comprehend direct Wisdom, the Buddha may have explained the manner in which karmic influences affect our lives, and how to apply wisdom and compassion in all of our actions. To those for whom such teachings would fail to point them toward their own Awakening, the Buddha may have taught them the Five Precepts to guide them in their lives.
This isn't some judgmental approach that proclaims a certain class of people as "better" or more advanced than others. Rather, it is the ultimate expression of compassion and wisdom, the BEST thing the Buddha could do for that person at that time in their particular circumstances. The Buddha taught that each of us has the ability to Awaken to the fullest extent, and out of his perfect compassion, he guided each person with whom he spoke toward their own Awakening at whatever level they were capable of benefiting.
Any honest look at the world around us, and the people with whom we live, clearly shows that there is no single approach to life that will "work" for everyone. I have many Christian friends who, in their hearts, "know" that faith in Christ is in the best interest of every single individual on the planet. However, a number of my experiences in life have directly contradicted what Christians believe is True (e.g. I have directly experienced some level of interbeing and non-self, which Christianity strictly opposes). Therefore, Christianity clearly does not "work" for me; it does not model my experiences of the world, and I find several teachings in its most holy book to be 100% unethical (the denouncement of homosexuality comes to mind). I would be forced to lie to myself and others if I attempted to follow its teachings. Note that this isn't meant to bash Christianity. In terms of skillful means, Christianity does "work" for many people and is therefore an important guide by which many people live their lives. This is simply a personal example of skillful means in my life.
1-Minute Contemplation: Is there someplace in your life in which you used unskillful means in relating to others? Maybe a friend of yours required gentle compassion and you chose to use "tough love." Or maybe you tried to forcefully persuade somebody to your view, when a more gentle "guiding" approach would have been what they truly needed to hear. Contemplate this situation for 1 minute. How might you have acted more skillfully?