The effect of these words is to call our attention to human responsibility, responsibility to respond to what God has to say. Every man and every woman is responsible for the state of their own soul, for its protection and eternal welfare. The word ‘if’ emphasises that there is a response required to what God has said, to his warning, faithfully given. But responsibility does not imply ability, and the right reaction of the one who hears these words is to immediately turn to God for help. This does not mean that he denies responsibility, but he admits his powerlessness to obey in an acceptable way without the help of the same Spirit of God who is speaking to him. We must hear God’s voice, but we are aware of sin within us which makes us want to stop our ears and follow our own desires. We must cry out urgently to the Lord for help in this matter.
You may have heard his voice yesterday. You may have been saved a month ago, ten years ago, thirty years ago, fifty years ago, but it is possible nevertheless that today you are not hearing his voice. Or you may hear it tomorrow but not the next day. The failure to heed the voice of God, which is the door to backsliding, can come so suddenly. The temptation can be launched and suddenly our minds are far away, and our interests and priorities are elsewhere, and we are swept aside. So the word which is emphasised here, strangely but significantly, is ‘today’. It is something we choose to do as Christians: to have our hearts open to the voice of God, in his word, obviously, primarily and chiefly. To be challengeable from the word, to be impressionable whenever we take up the word privately and read it. Equally to be challengeable and impressionable when we hear it proclaimed or read publicly.