"And I will cleanse them from all their iniquity, whereby they have sinned against me; and I will pardon all their iniquities, whereby they have sinned, and whereby they have transgressed against me. And it shall be to me a name of joy, a praise and an honour before all the nations of the earth, which shall hear all the good that I do unto them: and they shall fear and tremble for all the goodness and for all the prosperity that I procure unto it." (Jeremiah 33:8-9)
To say that the gospel is for others but not for you because you are too sinful is not to make a statement about yourself but about God. To say such a thing is not to say that you are not good enough, but that God is not good enough. To say that God only has grace for those who deserve it, but not for those who don't deserve it, is to say that God is really not a God of grace at all. In that case, there would be nothing essentially amazing about God at all. "Sorry guys, He is not really that good."
But the truth is that God is amazingly good. God is a God of amazing grace. And God's amazing grace is for you, no matter how sinful you are. That is what His grace is all about! To trust Him for your salvation is to say, "I expect to go to heaven, not because I am good but because you, God, are good." Therefore, if you are trusting in God's grace for your salvation and don't go to heaven, it will make God look bad. He could never, in that case, be praised forever as the God of mighty amazing grace. His glory is bound up in men and women trusting in His goodness (not their own), and not being disappointed.
So don't look to yourself and say such things. Look to God, and declare His glory.
"When we've been there ten thousand years,
Bright shining as the sun,
We've no less days to sing God's praise
Than when we first begun."