According to data released by Amazon on the most highlighted passage in Kindle ebooks, the most popular passage from the Bible is one on reducing anxiety and finding trust in God. See article here.
6 do not be anxious about anything, but in everything by prayer and supplication with thanksgiving let your requests be made known to God. 7 And the peace of God, which surpasses all understanding, will guard your hearts and your minds in Christ Jesus. Philippians 4:6–7 (ESV)