God tells us in His Word that believers are “justified freely by His grace through the redemption that is in Christ Jesus” (Rom. 3:24). The word “freely,” here, does not mean “without cost,” but “without cause.” The same original word is so translated in John 15:25, where we find the words of Christ: “They hated Me without a cause.”
Thus sinners hated Christ “without a cause,” yet God justifies sinners “without a cause.” How can this be? Let’s see:
What had Christ done to earn the enmity of men? Nothing whatsoever. He had been kind and good, had helped those in distress, had healed their sick, had made the mute to speak, the deaf to hear, the blind to see, and the lame to leap for joy. Why, then, did they hate Him: The Bible says they hated Him “without a cause, i.e., without any cause in Him. The cause of their hatred lay in their own evil hearts.
But on the other hand, what have sinners done to merit justification before God? Again the answer is: Nothing whatsoever. They have broken His commandments every day, lying, stealing, and committing hundreds of other sins. Yet in love God gave His Son to die for them on Calvary “that He might be just and [at the same time] the Justifier of him that believeth in Jesus” (Rom. 3:26). He loves and justifies believers “without a cause”, i.e., without any cause in them. The cause is to be found in His own compassionate heart, for “GOD IS LOVE.”
Thus those who trust in Christ, who died for our sins, are justified without a cause, by God’s grace, through the redemption that is in Christ Jesus.
“God commendeth His love toward us in that while we were yet sinners Christ died for us” (Rom. 5:8).
“By this man is preached…the forgiveness of sins, and by Him all that believe are justified from all things, from which He could not be justified by the law of Moses” (Acts 13:38,39). source