They didn't die because they didn't give all the money to the church. They died because they presumed they could LIE to GOD. They kept some of the money for themselves, but wanted the church, and God, to believe they had given everything. It was the pride and arrogance in their hearts that God was punishing. I think He wanted to impress upon the church the SERIOUSNESS of these sins. A kind rebuke would not have done that. God is compassionate, but He also disciplines those He loves. [Hebrews 12:6] He wants to develop godly character in His Children. [Romans 5:3-5] If these two were really Christians, then they still went to heaven, but "as one escaping through the flames."[1 Corinthians 3:15 NIV]