Since through God’s mercy we have this ministry

2 Corinthian 4:1-6 

Therefore, since through God’s mercy we have this ministry, we do not lose heart. Rather, we have renounced secret and shameful ways; we do not use deception, nor do we distort the word of God. On the contrary, by setting forth the truth plainly we commend ourselves to everyone’s conscience in the sight of God.  And even if our gospel is veiled, it is veiled to those who are perishing. The god of this age has blinded the minds of unbelievers, so that they cannot see the light of the gospel that displays the glory of Christ, who is the image of God. For what we preach is not ourselves, but Jesus Christ as Lord, and ourselves as your servants for Jesus’ sake. For God, who said, “Let light shine out of darkness,” made his light shine in our hearts to give us the light of the knowledge of God’s glory displayed in the face of Christ.

Why?

Paul's ministry is through God's mercy, not by any human beings.

Paul's preaching is Jesus Christ, and he and his co-workers are servants for Jesus' sake. Here Paul explained what and why he so hard to preach the gospel.

Jesus Chris is the light shining in the darkness, shining in our hearts, this is the light of the knowledge of God's glory.

How?

I am glad that I can be a Christian, I may have the light of Christ in my heart. This is the grace of the Lord on me.