"yes" and everything else
The response to God's offer of forgiveness, mercy, and love in Christ is not something we get to make up as we see fit. It's like when someone proposes marriage. There's "Yes" and there's everything else, which is "not Yes". In Christ, God both proposes and promises love--engagement and wedding combined. The "Yes" is clearly defined in Scripture: faith (complete trust in Jesus Christ), repentence, baptism, and the intention, with God's help, to live a life of obedience (or at least try one's level best). That's it. Anything else is "not Yes". That means a "decision for Christ" is, biblically speaking, not yet a "Yes"--find some water somewhere, finish what you started! Much less is something along the lines of "I'm so thankful for the love God has shown me, and I will try never to forget this feeling of gratitude." That's a "not Yes." You're flattered, but your Suitor is still on His knees, waiting.