Seek God while He may be found? Is. 55:6-7
“Come…Incline your ear…Hear and your soul shall live” (Is 55:1, 3). While our hearts are sensitized to Him (inclined and hearing), He can be found; He is near. But if we allow our hearts to get cold, we distance ourselves! Note the context: God abundantly pardons the wicked (v.7)! Are not His mercies new every morning (Lam 3:23)? Read all of Psalm 136.
Though God is abundant in mercy, there is yet a sense of urgency about the present. He deals with us for a season through grace; but if we persist in resisting Him, He judges us. And while we are being judged, He may be beyond our reach until our judgment lesson is learned. This verse does not say a time will come when we will never be able to find God, or that He will not find us. We must not read into this verse what is not there.
From Hope Beyond Hell Revised 2010 pages 224