The Greek ekpeirazō is an intensified form of peirazō (to test/tempt), meaning to put severely to the test — particularly the act of testing or tempting God. Satan quotes Psalm 91 to Jesus and says 'throw yourself down, for the angels will catch you' — Jesus responds 'Do not put the Lord your God to the test (ekpeirazō)' (Matthew 4:7; Luke 4:12), quoting Deuteronomy 6:16. Paul uses it in 1 Corinthians 10:9 as a warning from Israel's wilderness failure.
The specific sin of ekpeirazō — testing God — is the demand that God prove Himself by performing on command. Israel's wilderness complaint 'Is the LORD among us or not?' (Exodus 17:7) was the original context of the Deuteronomy 6:16 prohibition. Jesus refuses to test the Father by forcing a spectacular rescue. The cross was not a display-of-power moment but a moment of hiddenness — and the resurrection vindicated the One who trusted rather than tested. Paul's warning to Corinth: 'Do not test Christ as some of them did — and were killed by snakes' (1 Corinthians 10:9).