An implication which proceeds from Ps.16 is that it’s impossible to trust in God for an eternal security of our souls if we aren’t trusting in him for a present security of our souls. In other words, there is no way to have certainty that God will be our refuge when we pass from this life, if he is not already our refuge for us during this life. Just think about the kind of faith it takes to believe in our resurrection; that God will come fetch our decayed bodies just lying there lifeless in the grave and then recreate them in perfection as they are reunited with our souls. That’s some serious faith and that kind of faith will certainly manifest itself in this life.
That begs the question: How can God be our refuge or source of protection now? A portion of the text will lay it out nicely for us—It’s when we come under Christ’s lordship, when we delight in Christ’s people and we refuse any substitute for Christ’s worship. Perhaps a great summary can be found in the negative from the mouth of Jesus in Luke 6:46—Why do you call me lord, lord and not do what I tell you? In other words, why do you profess to come under my protection of lordship if you don’t desire to obey me in all things? And then of course, Christ says in Matt. 7 that many who call him lord, don’t really know him at all, inferring that they were presuming to find refuge in God in the afterlife apart from finding refuge in his protection of lordship throughout their lives.
Often the reality of our finding refuge in God is greatly tested when pressure comes into our lives through the various trials of living a sin-stained life in a sin-cursed world. When it comes upon us, does our security quickly flee from us or is the meditation of our thoughts a practiced consideration of who God is for us and what Christ has secured for us? In other words, how he is and will be a refuge for us? This is what gave David hope in this life and in the one to come.