What does it means that everyone has to give an account to God (Christ)?
"But why do you judge your brother? Or why do you show contempt for your brother? For we shall all stand before the judgment seat of Christ. For it is written: "As I live, says the LORD, Every knee shall bow to Me, And every tongue shall confess to God." So then each of us shall give account of himself to God" (Romans 14:10-12).
It basically means we will face the Judge of all the earth and explain why we chose to do the things we did. The point is we stand individually before God and cannot hide behind anyone else or any organization. "But let each one examine his own work, and then he will have rejoicing in himself alone, and not in another. For each one shall bear his own load" (Galatians 6:4-5).
"For we must all appear before the judgment seat of Christ, that each one may receive the things done in the body, according to what he has done, whether good or bad" (II Corinthians 5:10).
Nor are the opinions of other going to be the standard of judgment. "He who rejects Me, and does not receive My words, has that which judges him -- the word that I have spoken will judge him in the last day" (John 12:48). Ultimately it isn't whether I or anyone else thinks a person should or should not go to heaven. We don't know everything. We can't see a person's thoughts or motives. The decision is left to the impartial Judge does know all. "Therefore judge nothing before the time, until the Lord comes, who will both bring to light the hidden things of darkness and reveal the counsels of the hearts. Then each one's praise will come from God" (I Corinthians 4:5). All any of us can do is teach what the Lord commanded because that is the standard to which all of us will be held.
And the judgment with be thorough and complete. "But I say to you that for every idle word men may speak, they will give account of it in the day of judgment" (Matthew 12:36).
"Let us hear the conclusion of the whole matter: Fear God and keep His commandments, for this is man's all. For God will bring every work into judgment, including every secret thing, whether good or evil" (Ecclesiastes 12:13-14).