That is gravely sinful. The sin is presumption of salvation. Think again.
God promises it.
I believe Him in faith.
He confirms in my Spirit and in His Word I am His.
To believe God is always right.
To reject the One payment He made for all sin in unbelief, is to decide you prefer hell.
Hebrews 11:1 Now faith is the assurance of things hoped for, the conviction of things not seen.
I John 5:10-15 Whoever believes in the Son of God accepts this testimony. Whoever does not believe God has made him out to be a liar, because they have not believed the testimony God has given about his Son. And this is the testimony: God has given us eternal life, and this life is in his Son. Whoever has the Son has life; whoever does not have the Son of God does not have life. I write these things to you who believe in the name of the Son of God so that you may know that you have eternal life.
And this is the confidence that we have toward him, that if we ask anything according to his will he hears us. And if we know that he hears us in whatever we ask, we know that we have the requests that we have asked of him.