Since God is good, and we are not good, it would not be unjust of God for Him to be our enemy. In fact, everyone who is born into this world is born as an enemy of God, and under the curse of God, and the only end they are appointed to from the day of their birth is the fire of hell. Yet, God’s goodness is so great, that even though we have offended Him every day of our lives, and have done nothing but merited His judgment, His heart’s desire is for us to escape His wrath. Yet, how can God do this for us, when justice demands our destruction?
This is what God did. About 2,000 years ago, God sent His Son into the world, to be born as a human being from a virgin’s womb, and He grew up among the people which He made. When He was 33 years old, the whole world rejected Him, and crucified Him, (no God did not replace Him with someone else on the cross. That would make Him a deceiver, which is what Allah is). After Jesus bled and died on the cross, they put Him in a tomb, and they rolled a stone over it. But three days later, God raised Him from the dead. The whole purpose behind this whole thing was for Christ to suffer under the full wrath of God, (not just the nails in His hand and His feet, and the spear which pierced His side), while He was hanging on the cross, and to bear the penalty for the sin of every human being who ever lived, or who would live from that time on. Since the price has been paid, God no longer has to punish us for our sin, because He has already poured out His wrath on a sinless man, (who was also the incarnate God), and judged Him as if it were all of us hanging on that cross.
And now, all that God requires from us is that we believe in Jesus Christ, and acknowledge that we have broken His law, and are not worthy to escape His wrath, and that the blood which Christ shed on the cross is what makes us acceptable in His sight. If we reject Christ, then we are guilty of the death of Christ, and our punishment will be severe. So now, if you have never believed in Jesus Christ, in the way that it has been explained here, I encourage you to place your faith in Him. And if you do this, He will send His Holy Spirit to live within you, and the Holy Spirit will work on your heart to make you more and more like Christ, and He will make you aware of your sin when you have sinned against God, urging you to repent so that your fellowship with Him will be restored. Also, you should read the Bible in order to learn what God expects from you.