# But if our gospel is veiled, it is veiled only to those who are perishing

See 2 Corinthians 3:14. There Paul explained that there is a spiritual veil that prevents people from understanding when they read the old covenant. In the same way, people are not able to understand the gospel. 

# if our gospel is veiled, it is veiled

"if a veil covers our gospel, that veil covers it" 

# our gospel

"the gospel that we preach"