If the Calvinist understanding of “dead in trespasses and sins” were true, the prodigal son would never have returned home. The prodigal son would still be a prodigal because he would have no ability to do anything at all, since he was dead.
Yet we see that despite the fact that the prodigal son was dead to his father, he still had the ability to choose to return. What was it that brought him home? His choice.
“I will arise and go to my father, and will say unto him, Father, I have sinned against heaven, and before thee” Luke 15:18.
Notice he said, “I WILL.” Returning to God is a choice that a sinner must and can make. Those who are dead in their trespasses and sins, like the prodigal son, still have the will power necessary through which they can return to the Father.
“For this my son was dead, and is alive again; he was lost, and is found. And they began to be merry.” Luke 15:24