How can non-believers, who cannot perceive nor understand the things of the Spirit, overcome their spiritual blindness?

Suppose a non-believer is open to the possibility that God and the things of the Spirit might exist, but acknowledges that for them subjectively God appears to be *hidden* and thus feels unable to perceive and understand spiritual matters, fitting the description of *spiritual blindness*. If a non-believer in such a state is proactively interested in opening their "spiritual sight", so to speak, and overcome their *spiritual blindness*, what would they need to do to accomplish that goal, from a Christian perspective on the issue? I ask this as a follow-up to my last question, *https://christianity.stackexchange.com/q/97717/61679* . Regarding the definition of *spiritual blindness*, I'm borrowing the definition from GotQuestions.org: > To be spiritually blind is not to see Christ, and not to see Christ is not to see God (Colossians 1:15-16; 2 Corinthians 4:6). Spiritual blindness is a grievous condition experienced by those who do not believe in God, Jesus Christ, and His Word (Romans 2:8; 2 Thessalonians 2:12). Those who reject Christ are the lost (John 6:68-69). Being spiritually blind, they are perishing (2 Corinthians 4:3-4; Revelation 3:17). They choose not to accept the teachings of Christ and His authority in their lives (Matthew 28:18). They are blind to the manifestations of God as revealed throughout His Word and Jesus Christ (John 1:1; Acts 28:26-27). They are described as those who “do not accept the things of the Spirit of God, for they are folly to him, and he is not able to understand them because they are spiritually discerned” (1 Corinthians 2:14). > > https://www.gotquestions.org/spiritual-blindness.html