There are many different reasons why people turn to God in Christianity. One of those is the promise of future reward from God. On the surface it seems a somewhat selfish motive, but it does go deeper when the full picture is considered.
Colossians 1:3: To the saints and faithful brothers We give thanks to God the Father of our Lord Jesus Christ, praying always for you, 4 having heard of your faith in Christ Jesus, and of the love which you have toward all the saints, 5 because of the hope which is laid up for you in the heavens, whereof you heard before in the word of the truth of the gospel, WEB
Here in Colossians, it is a hope laid up in heaven that is put up as basis for the faith in Jesus. It raises the question of just what the “hope” is. In this context, a “hope” is a confident expectation of something positive yet to happen in the future. In this case it is a particular promise held with God.
Matt 16:27: For the Son of Man will come in the glory of his Father with his angels, and then he will render to everyone according to his deeds. WEB
It is the promise of the return of Jesus to the earth and a new life living in the world ruled directly by God. When the disciples of Jesus saw him taken up into heaven, the quite specific promise of return was reiterated when angels said,
Acts 1:11: "You men of Galilee, why do you stand looking into the sky? This Jesus, who was received up from you into the sky will come back in the same way as you saw him going into the sky." WEB
But with this return is associated also the personal hope for individuals. It is the promise of a changed life without evil and death.
1 Corinthians 15:50: Now I say this, brothers, that flesh and blood can't inherit the Kingdom of God; neither does corruption inherit incorruption. 51 Behold, I tell you a mystery. We will not all sleep, but we will all be changed, 52 in a moment, in the twinkling of an eye, at the last trumpet. For the trumpet will sound, and the dead will be raised incorruptible, and we will be changed. WEB
It is this new changed body and environment for the world that people associate so closely with that hope laid up in heaven. Perhaps it coul be considered to be like the hope of the new birthday toy laid up for a child in the parent's wardrobe. There are certain similarities, in that it is a blessing waiting to be given.
One may then ask whether this is a selfish hope. Is it just the wanting of the new gift from God? At a superficial level it may seem for self, but this is without understanding the fullness of the gospel message. Continuing in Colossians 3, there is an explanation,
Colossians 3:1: If then you were raised together with Christ, seek the things that are above, where Christ is, seated on the right hand of God. 2 Set your mind on the things that are above, not on the things that are on the earth. 3 For you died, and your life is hidden with Christ in God. 4 When Christ, our life, is revealed, then you will also be revealed with him in glory. WEB
The basis of the gospel is much deeper than the hope of receiving handouts from God. It is bound up in the forming of a relationship with God through Jesus. The promise of being part of the Kingdom of God is one where we see ourselves in the context of being part of a combined body in Jesus, and look to the glory given to God.
It isn't something about individual achievement, but rather seeing God's success and glory on earth, and seeing it as part of his team.
