A causal and explanatory conjunction — 'for,' 'because,' 'indeed.' Gar introduces the reason or ground for the preceding statement. It appears over 1,000 times in the NT, making it essential for following Paul's logic and understanding why the gospel is what it is.
Some of the most important theological statements in the NT are gar clauses — the 'because' behind the gospel. 'For God so loved the world' (John 3:16). 'For the wages of sin is death' (Romans 6:23). 'For by grace you have been saved' (Ephesians 2:8). 'For I am not ashamed of the gospel' (Romans 1:16). The conjunction reveals that Christianity is not just proclamation but reasoned proclamation — there is always a 'because.'