What does Paul mean when he says 'our heart is enlarged' in 2 Corinthians 6:11?
Paul means his heart was enlarged in love for the Corinthians—an expansive, open affection that enveloped them despite their carnality and failures. He was not restricting them; rather, any narrowness or restraint was in their own innermost being, their own heart, not in his love toward them.
Les explains that 2 Corinthians 6:11 comes as Paul addresses the Corinthian church, which was still carnal and babes in Christ, not mature like the Ephesians or Philippians. Even so, Paul's love for these carnal believers was real. When Paul says 'our mouth is open unto you,' he means he could speak freely to them and they heard everything he said. 'Our heart is enlarged' means his love was just enveloping them in spite of their failures. By contrast, 'you are not straightened in us' means Paul was not the one holding back; they were straightened in their own bowels, a Hebraism for the innermost being, heart, or soul. Les teaches that the gospel had taken hold enough to bring them out of paganism, and they had separated from their pagan background to a degree, but they were still carnal and had a long way to go. So the enlarged heart is Paul's expansive, open love, while the constraint was on their side.
O ye Corinthians, our mouth is open unto you, our heart is enlarged.