That's a good verse. Both aspects are illustrated. The word to some is offensive and they are disobedient to it. Those are people who are not elect. So if someone were to say to you that they worry that they might not be elect. What do you tell them? "Yep. You may not be and if that's the case then sorry about your luck." Of course not. You tell them like Owen did, that Christ has made everything ready for them and if they will repent and believe they will be saved. They will indeed and in truth are "elect" if they do.
The difference between a semi-Pelagian and a Calvinist is that the semi-Pelagian believes that when I say they are elect if they do repent and believe - they believe that all the universe waits to see what their decision will be. The Calvinist believes that the elect really are the ones who will repent and believe - yet, and this is the most important part, the elect really and truly must,(and will) repent and believe.
Within that framework we all have to figure out some concept of how this works in our own individual minds. Plenty of people leave it that you must make the final decision and therefore it indeed is up to you. Then there are various beliefs about how much the Holy Spirit works and convicts and convinces and leads to faith or gives faith and whether this can be resisted. Those that lean toward the decisive factor being the work of the Holy Spirit would include 5 point Calvinists like Owen all the way to 4 point Calvinists or "moderate" Calvinists like J.C. Ryle or Ware, or any Baptist or Evangelical preacher who warns in his preaching not to trifle with the Holy Spirit because you can't come unless he calls and this call is personal and not in your control.
We can have differences in our background theology and yet there still be a lot of overlap in actual preaching and practice. Or, we can be so unable to balance scripture that we go extreme and unscriptural one way or the other. In my opinion, Owen, and Ryle and all the Puritans and Edwards and Bonar and Spurgeon and Baxter and Wesley were all within this range and any good Baptist, Calvinist or not, can get a lot of good out of any of those guys. If you are not a Calvinist, or even if you hate Calvinism, I promise you a great blessing if you read the sermons of any of those guys.