How do I share the gospel with agnostics?

from the old testament

• Often the most compelling evidence of God is what is right in front of us: creation. As David wrote, "The heavens declare the glory of God, and the sky above proclaims his handiwork. Day to day pours out speech, and night to night reveals knowledge" (Psalm 19:1-2; cf. Romans 1:20). Our experience tells us that such complexity cannot be accidental.

from the new testament

• Agnostics, by definition, are more open to the idea of God than atheists are. Believers can encourage agnostics to earnestly seek God, asking Him to reveal HImself. The apostle Paul noted that God puts all people in circumstances that allow them  to know him, though "he is actually not far from each one of us" (Acts 17:27).
• Agnostics and other unbelievers often point to the suffering in the world to defend their ambivalence about the existence of the God of Christianity. Believers can counter this argument by showing that moral sensitivity is itself evidence for God (Romans 2:15); moral laws and duties require a Lawgiver: God.
• Often, the best testimony of the power of Christ in one's life is a Christian's interactions with unbelievers. Believers should share the truth with "gentleness and respect" (1 Peter 3:15), which encourages further conversation.
• Christians are responsible for "contend[ing] for the faith that was once for all delivered to the saints" (Jude 1:3), but they're not responsible for conversions. Only the Holy Spirit changes hearts (2 Corinthians 4:6). Christians are gardeners, not the One who gives the growth (1 Corinthians 3:7). Believers should share the gospel with agnostics and pray to God to give help them see the truth.
• Agnostics' resistance to accepting the truth could be similar to those Paul spoke of as "always learning and never able to arrive at a knowledge of the truth" (2 Timothy 3:7; cf. Acts 17:21). A revealing question to ask an agnostic is, "Would you become a Christian if you knew Christianity were true?" This may help them to understand if their indecision is based on incomplete knowledge or a heart resistant to God (John 3:19).

implications for today

"Recalculating"—that can be frustrating on a GPS, but wise if you're mulling over an important decision. Sooner or later, though, you have to move forward.

In many ways, agnosticism can become a perpetual "recalculating" state. There is nothing wrong with asking honest questions or wrestling with difficult issues—God is not threatened by sincere seekers. But some people become so comfortable examining possibilities that they never commit themselves to the truth, even when the evidence points them there. The search itself becomes the destination.

Spiritually, though, the destination is not simply more information—it is Jesus Christ. Christianity is rooted in history, not wishful thinking. Believers can point to reasons for faith: the existence of God, the historical reliability of the Bible, the evidence for Jesus' life, death, and resurrection, and the transformation of countless lives throughout history. We should welcome questions and thoughtfully engage with those who have them. But no amount of evidence can make a decision for someone else. We can point to the road, but we cannot get in the driver's seat and choose it for them.

At some point, every person must answer Jesus' question: "Who do you say that I am?" (Matthew 16:15). Choosing not to decide is, in the end, a decision. The Bible teaches that every person will live forever. The question is not whether eternity exists but where we will spend it. That is determined by what we do with Christ today. God lovingly invites every person to come to Him, but He does not force anyone to follow Him. Eventually, the time for recalculating ends, and the destination we've chosen becomes the one we reach.