This question does come with an admittedly large number of assumptions behind it. It assumes, for instance, that you will die this very night which is a hopefully unlikely event. But considering that death will one day take you then it is not so much an assumption as a jump ahead in time to that day when death will come. Another assumption the question makes is the existence of God and the need to defend yourself before him. We'll get to these momentarily. Suffice to say, this question is of no small significance and deserves sober reflection for the matters it touches upon are of eternal importance.
There can be nothing more important that our standing before our Creator. So many people think about God the wrong way round. They ask themselves: "What do I think of God?" when a far more vital question is: "What does God think of me?" It may be that you are perfectly happy with the idea that God exists. But what does God think of your existence and life before him?
The question above helps to get us to consider these issues. It is, I hope, a useful question to ponder. For death has a way of stripping us of all illusions and delusions and focusing our minds away from trivial matters and onto weightier ones. Naked we enter the world and naked we depart. Wealth, talent and success just isn't going to be of any use in death for we take nothing with us.
The natural first defence would be simply that God doesn't exist. Though, if you were indeed standing before God and denying his existence it would be a rather unsuccessful argument. Perhaps a better defence would be: "You gave me no evidence of your existence." After all, that is the main argument of atheists - God's existence cannot be proven.
Would such an argument carry any weight? God's revelation to humanity, as found in the Bible, suggest not:
"For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse. For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened." (Romans 1v20-21)
Denial of God's existence is not down to lack of evidence but lack of belief. The universe stands as a testament to God's existence and power. Again, as it says elsewhere in the Bible: "The heavens declare the glory of God." Not hint or give a vague suggestion of, but declare his glory. So people are without excuse; their problem is not that there was no evidence but that seeing the evidence they choose to reject it.
Secondly, it could be argued that while God exists there is no need to give a defence before him because he does not require one. This could be for a variety of reasons. God might be unconcerned with our actions, caring little for our opinion of him or beliefs about him or the idea of God as Judge might be an alien concept. But again, this defence falls short.
As Peter's letter reminds us: "For you have spent enough time in the past doing what pagans choose to do—living in debauchery, lust, drunkenness, orgies, carousing and detestable idolatry. They are surprised that you do not join them in their reckless, wild living, and they heap abuse on you. But they will have to give account to him who is ready to judge the living and the dead." (1 Peter 4 v 3 - 4)
Jesus Christ is coming once more and rather than salvation he will bring a final judgement of the living and the dead.
A few verses before our last quote from Romans it says: "The wrath of God is being revealed from heaven against all the godlessness and wickedness of people, who suppress the truth by their wickedness, since what may be known about God is plain to them, because God has made it plain to them." Romans 1v18-19
Notice the present tense of the verb in the first sentence, God's wrath is being revealed in the present against the wickedness of humanity. God has 'made it plain' to people that he is angry at sin. How is this made plain to people? Well, look no further than the newspapers and their record of all the evils and miseries of our world. When Jesus talks about the problem of suffering his answer is "But unless you repent, you too will all perish." The brokenness of our world, ourselves and our relationship with God is meant to point us to the fact that God's wrath is set against sin.
Given the failure of the last two arguments it might seem tempting to argue: "Well ok, God exists, he is wrath against sin, I have no excuse, but I'm a good person! God will surely look upon me with favour. I'm too good to go to Hell!" To rephrase this with another question: "surely my own righteousness is enough to merit my salvation?"
The answer to that question is a resounding, deafening, absolute, no. Take the two greatest commandments: love God with all that you are and love your fellow man as yourself. Do you have a perfect track record of obeying both? Can you proclaim to have a perfect righteousness? For before a holy God no other works based righteousness will stand. Rightly then, the Bible declare that there is "no one good, no not one." (Romans 3v12) and "All have sinned and fall short of the glory of God. (Romans 3v23)" It says: "for whatever is not from faith is sin" (Romans 14v23) and that all our good works are like dirty rags (Isaiah 64v6) when it comes to justifying us before God.
Unable to defend ourselves based on our own works we might then make claim to the love of God. "How can a loving God send me to Hell? Surely a God of love will let me into heaven?" This reveals only a rather narrow view of love. The fact that God is love does not make him some omni-benevolent old man in the sky type figure, unconcerned with our rebellion and sin before him. The Bible paints a richer view: God is love and his love is a holy love, a love which hates evil and a love which declares that the wages of sin is death. How could a God of love allow evil into his presence? Has not the Judge of all the earth got to do right? Does love not require that the cosmic treason of sin be dealt with?
There are likely many more excuses and potential defences we could try and make. Our ingenuity in excuse making has a boundless capacity after all. But ultimately, there is only one defence that can be made before God: the work and person of Jesus Christ.
Salvation is found through no one else; here we find God's love on glorious display, in sending his own Son, to die for rebel sinners, to die for those who hated him, to love us first before we could ever love him. Jesus is the God-Man, who lived that perfect live we could not live and died a death we deserved to die and became sin for us that we might stand before God completely righteous.
Before God, there is only one plea: Jesus Christ. He is our Saviour. We did not ask him to save us but willing he humbled himself and went to a death on a cross to win for us a salvation we did not deserve. And having died, he was raised to live, to prove his victory over sin and death. This is the heart of Christianity, this is the good news, that there is salvation to be had! We can be right before God. We can stand before him with a freedom and a confidence and a joy and a peace. But to do so we must believe in Christ, for there is no other way to be saved.
As Peter testifies about Jesus Christ: "He himself bore our sins in his body on the cross, so that we might die to sins and live for righteousness; by his wounds you have been healed. For you were like sheep going astray, but now you have returned to the Shepherd and Overseer of your souls." (1 Peter 2 v 24 - 25)