"For none of us lives to himself, and none of us dies to himself. For if we live, we live to the Lord, and if we die, we die to the Lord. So then, whether we live or whether we die, we are the Lord's. For to this end Christ died and lived again, that he might be Lord both of the dead and of the living." (Romans 14:7-9 ESV)
If I have entrusted myself to the Lord in faith and repentance, then I am his. If I am his in this life, I will be his in the next. This is a tremendous peace-bringing truth! I need fear nothing in life or death, because Jesus is Lord over all the living and the dead. People who live only for this life will see traumatic discontinuity as they face death. People who live for Jesus will see great continuity between this life and the next, for they belong to him who is Lord over both realms.
This is also one of the keys to being gracious, gentle and encouraging to our fellow believers who may differ with us on non-essential points of doctrine or practice. Here's how I should view other believers -- they don't belong to me, they belong to the Lord. They do what they do out of reverence for Christ, as I should be doing. This enables me to have a peace with, and a generous amount of tolerance for, other believers and their convictions. I am not to flaunt my liberties or convictions to the point of offending the conscience of other believers or hindering their growth.
The kingdom of God is about "righteousness and peace and joy in the Holy Spirit." (14:17)