Many religious people are legalistic and are under the law. They think in terms of the minimum necessary in order to please God. This is why they calculate exactly how much 10% of their income comes to and then offer it reluctantly to God. In the Old Testament, this attitude finally ended up in the Israelites offering blind sheep and sick bulls as sacrifices to the Lord (Mal. 1:8).
It is possible to have an identical attitude to the New Testament commandments. A sister can think in terms of the minimum necessary in order to keep the letter of the Word that commands her to be subject to her husband; or the minimum necessary covering required for her head in the meetings - without the beauty of her hair being totally hidden! Men and women can think in terms of the minimum necessary in order to be 'spiritual' without altogether giving up everything. "What is the minimum that I have to give up of this world?" is a question that is always in the minds of such people. Such people can never be spiritual. They can only be religious.
Jesus' attitude was totally different. He never sought to discover what the minimum requirement was, to please His Father. On the contrary, He sought to find out what the maximum was, so that He could offer everything to the Father. Therefore He sought to find out the spirit behind each commandment. Thus He knew that it was not enough to merely avoid adultery in the flesh (even though that was the minimum required by the law). He understood that the spirit behind that commandment was that one should not even lust (covet) in one's heart. Likewise, He saw that anger and murder were similar. And so on. Thus, He understood the spirit behind each commandment.
An earthly bride who is deeply in love with her bridegroom never thinks of the minimum necessary to please her partner. On the contrary, she thinks of what the maximum is that she can do. This is the attitude of the bride of Christ too.
It is here that we see the distinction between the servant and the bride. Those under the law can only be servants. The employee works for wages and is therefore very calculative in his service. He measures his work by the clock. If he works overtime, he expects extra wages. One who is a son (or a wife), on the other hand, will work for any length of time - not for reward, but out of love. Herein lies the difference between religiosity and spirituality.
The attitude of mind that thinks, "What can I get out of the Lord?", leads to religiosity. On the other hand, the attitude that thinks, "What can the Lord get out of the one earthly life that I have?", will lead to true spirituality. It will then become natural for us to go the second mile when the minimum requirement is to go just one mile