deal with the devil

An agreement, bargain, deal, or exchange with a powerful but ultimately malevolent force in which a person sacrifices or abandons moral, ethical, or spiritual values in favor of wealth, power, or other benefits. The legend of Faust, who sold his soul to Mephistopheles for unlimited knowledge and power, might be the best-known example of a deal with the devil. I fear we might have made a deal with the devil when we became so dependent on technology, having traded in every speck of our private lives for convenience and flashy gadgets. She gained massive political influence by courting powerful corporate lobbies, but this deal with the devil alienated her from all her former allies in Washington.