Paul’s defense in Acts 26 has a theme of how gospel ministry opens the eyes of the blind upon repentance and faith in Jesus Christ.
This understanding is essential as we think about our own salvation and our ministry to others.  Reason being, we will not give God the glory he deserves for saving us if we do not comprehend our desperate plight before conversion.  It’s absolutely certain that we had no chance of turning to God were it not for his supernatural work of the Spirit in our hearts.
This personal understanding directly relates to how we think about our ministry to others as well, for if we don’t understand our own blindness and life in the darkness of sin prior to Christ’s grace exploding into our life, then we will view others who are resistant to the truth as imbeciles and those who deserve to be condemned for their sin.  After all, we found the path of Christ—why won’t they do it?  The Bible teaches that unless God opens their eyes through hearing the truth, they neither desire nor have the ability to find the way of salvation.  That truth helps us maintain our compassion for the lost and will increase our usefulness to God’s purposes.