You are not called to believe in your love to God, but in God's love to you! Do not argue, 'I cannot love God! I have striven to my uttermost to do so, but have failed in all my endeavors, until in despair I have abandoned the thought and relinquished the attempt.' Be it so- no effort of your own can strike a spark of love to God from your heart. Nor does God demand the task at your hands. All that He requires of you is faith in His love, as embodied and expressed in Jesus Christ to poor sinners.