No one is forced to sign up for mountain climbing. You do it because it grabs you. There is a wild, passionate desire to go up there. And when the going gets rough you don't complain "My life is so hard."
The Sermon on the Mount is Jesus' introduction to his kind of a climb. Some people view it as God's way to make us feel guilty so we grovel and beg for forgiveness. But it's more like a movie of an Everest ascent. "This is what you will learn to enjoy if you stick with us in this course."
Climbing has its perverse pleasures. You see a woman dangling on a rope in a sleet storm, and you want to call out the rescue team and the St. Bernard dogs. But back in the lodge that night she glows with excitement as the others say "That was a great climb. I liked the way Lisa kicked herself away from the cliff till the rope swung her out onto that ledge."
The Beatitudes express this quirky idea of fun: "Blessed are the poor, mourners, the meek, the merciful, peacemakers, the persecuted."
When you begin you can of course make stupid mistakes and get away with it. As you go on, the safety of the other is more important than your own. Eventually the coach intends to make you perfect for peak achievement. Climbing Everest needs some training, but it is mainly a mindset that gets you there.
Most cultures think murder is wrong, but perfection needs the expert climber's "But I say to you." If you merely avoid the act, you never learn how murder is the opposite of loving. Love gets angry, but cools off before murderous anger takes hold. Love never says raca which says "You are a non-person. I never want to bother with you again." Nor does God's kind of love ever treat anyone like a stupid idiot.
Similarly with adultery. Even short term partners think it is wrong to have an affair on the side. But our mountain guide says "But I say to you that everyone who looks at a woman with lust has already committed adultery with her in his heart." At first sight that sounds like a way to condemn us for finding the opposite sex attractive. But since God designed us to feel that way, surely he doesn't fault us what he invented.
Jesus explains what he means with an illustration from archery. "If your right eye or right hand causes you to sin, tear it out and throw it away." The right eye is used for aiming, and the right hand pulls back the bow string. Archers can't help itching to take aim at all sorts of targets. But it's only when a decision is made to put an arrow on the string, pull back the string, and take aim that adultery occurs. And it occurs even when you miss, or you hurriedly put the arrow away when you see the owner.
The object of the mountain climbing sermon is not to condemn us but to introduce us to the kind of training that is needed. And when disciples enroll to begin learning they know very little. The trick is to trust the coach to take you in hand for perfection.