Paul doesn't mince words here. He's not suggesting that these sins might keep you out of God's kingdom. He's stating with absolute certainty that they will.
Certainty of Exclusion
The phrase "For this ye know" (ἴστε γινώσκοντες in the original Greek, as noted by scholars like Meyer and Ellicott) is a powerful appeal to the readers' existing understanding. It’s not just a statement of fact, but an emphasis that this is a truth they already recognize or should recognize based on the gospel they've received.
This certainty is crucial. Paul isn't offering a conditional warning that could be overcome by good deeds. Instead, he's laying out a non-negotiable reality: those who habitually engage in sexual immorality, impurity, or covetousness have no inheritance in God's kingdom. This is a definitive statement about the nature of God's reign and who belongs there.