How you can know for sure you are going to Heaven when you die

Hebrews 6:1-8

[1] Therefore let us leave the elementary doctrine of Christ and go on to maturity, not laying again a foundation of repentance from dead works and of faith toward God, 

[2] and of instruction about washings, the laying on of hands, the resurrection of the dead, and eternal judgment. 

[3] And this we will do if God permits. 

[4] For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, 

[5] and have tasted the goodness of the word of God and the powers of the age to come, 

[6] and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt. 

[7] For land that has drunk the rain that often falls on it, and produces a crop useful to those for whose sake it is cultivated, receives a blessing from God. 

[8] But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned. (ESV)