“A sinner is justified and reconciled with God the moment he truly believes in the person and atoning work of Christ. However, the evidence that he truly believed and was genuinely converted in that moment is that he goes on believing and confessing all the days of his life. This is not to say that the true believer will be immune to doubts, free from failure, or unhindered in his growth to maturity. However, it does mean that the God who began a good work in him will continue perfecting that work until the final day. Salvation is by grace alone through faith alone. However, the evidence of saving faith is a genuine and enduring confession of the lordship of Jesus Christ throughout the believer’s life”.
Paul Washer, The Gospel Call and True Conversion (Recovering the Gospel Book 2)