Our hearts are continuously rebellious. Every time we sin in thought, word, or deed, we're essentially saying in that moment that, "I don't need you God. I don't want you God. I like my way better than your way." If this goes on day after day after day, year after year, month after month, it would understandable for God to say, "I've given you ten trillion tries. You're finished." But it's not. So in that sense, His grace is always surprising, never ceases to be amazing and His mercy is remarkably outrageous.