A helpful observation that applies to preaching with authority and to the lordship salvation question:

The gospel “is not, then, a system of how people get saved. The announcement of the gospel results in people being saved – Paul says as much a few verses later [in Romans 1]. But ‘the gospel’ itself, strictly speaking, is the narrative proclamation of King Jesus. He [Paul] can speak equally of ‘announcing the gospel’ and of ‘announcing Jesus’, using the term kerussein, ‘to act as a herald’ in each case (e.g., 1 Corinthians 1:23; 15:12; 2 Corinthians 1:19; 4:5; 11:4; Galatians 2:2; 1 Thessalonians 2:9). When the herald makes a royal proclamation, he says ‘Nero (or whoever) has become emperor. He does not say ‘If you would like to have an experience of living under an emperor, you might care to try Nero.’ The proclamation is an authoritative summons to obedience – in Paul’s case, to what he calls ‘the obedience of faith’.”

N. T. Wright, What Saint Paul Really Said (Grand Rapids: Eerdmans, 1997), 45.