Charles Spurgeon Commentary John 5:18

"For this cause therefore the Jews sought the more to kill him, because he not only brake the sabbath, but also called God his own Father, making himself equal with God." — John 5:18 (ASV)

They did not understand him to preach Unitarianism; they understood him to proclaim his own true and proper Godhead, and he never contradicted them, for he was God.