Question: If you were to die today, how do you know you would be in heaven? This is an important question to be sure and worth consideration. But, you may NOT die today- then what? To deal with the first question is solved by consulting the Bible for the answer (Jn. 3:16; Lk. 13:1-3; Mt. 10:32f.; Acts 2:38; 1 Tim. 4:6-8 and Rev. 2:10c). That second question is the practical application of the first, for Christians must live a life of godliness. Paul says...
Philippians, Chapter 1 (WEB)
12 Now I desire to have you know, brothers, that the things which happened to me have turned out rather to the progress of the Good News; 13 so that it became evident to the whole palace guard, and to all the rest, that my bonds are in Christ; 14 and that most of the brothers in the Lord, being confident through my bonds, are more abundantly bold to speak the word of God without fear. 15 Some indeed preach Christ even out of envy and strife, and some also out of good will. 16 The former insincerely preach Christ from selfish ambition, thinking that they add affliction to my chains; 17 but the latter out of love, knowing that I am appointed for the defense of the Good News.
18 What does it matter? Only that in every way, whether in pretense or in truth, Christ is proclaimed. I rejoice in this, yes, and will rejoice. 19 For I know that this will turn out to my salvation, through your supplication and the supply of the Spirit of Jesus Christ, 20 according to my earnest expectation and hope, that I will in no way be disappointed, but with all boldness, as always, now also Christ will be magnified in my body, whether by life, or by death. 21 For to me to live is Christ, and to die is gain. 22 But if I live on in the flesh, this will bring fruit from my work; yet I don’t know what I will choose. 23 But I am in a dilemma between the two, having the desire to depart and be with Christ, which is far better. 24 Yet, to remain in the flesh is more needful for your sake. 25 Having this confidence, I know that I will remain, yes, and remain with you all, for your progress and joy in the faith, 26 that your rejoicing may abound in Christ Jesus in me through my presence with you again.
27 Only let your way of life be worthy of the Good News of Christ, that, whether I come and see you or am absent, I may hear of your state, that you stand firm in one spirit, with one soul striving for the faith of the Good News;
Whether you live or die, (today, or any other day) if you have followed God's will for your life to the best of your ability, then God will reward you according to what you have done. He makes the rules, HE paid for your sins, HE is the one who judges your fate- whether that fate ultimately will be heaven or hell is your judgement of whether or not to listen and do what HE wants. So, do it already and live!!!