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All good answers. But I do not forget that it is not any 'one thing'; not just accepting Christ, not just being compassionate, not just being a loving person. It is all of the fruits of the Spirit.
In James 2:24, It says, in my Bible, you are not saved by Faith alone, but also Works.
Going to heaven involves our whole being, our mind, our body, and our heart. Going to heaven may involve how much fruit we bear, for the Kingdom. (Remember the Parable of the Coins.)
Even considering all this, we still have to remember that God is not bound to do anything. We are totally at His mercy.
One last thought, Predestination. Who was chosen before the foundation of the Earth?
God want us to have joy, but not be so sure of our salvation we become prideful. That is where the Fear of the Lord comes in.
Only the righteous (Saints) will enter there, after they have accepted the Lord as their personal Savior.