With all due respect, your reply examples ignorance and superficiality, such as is typical with atheists. Why did God not use another means other than killing His Son so that those who choose the Light over Darkness may have eternal life? Because what keeps man from eternal life, and warrants the opposite, is that of misusing and abusing the good things God gave him, breaking His good laws which only benefit man when obeyed, and to man's hurt insofar as they are not, depending upon the degree thereof.
And according to a principle of justice, which requires that transgressions be punished then either the guilty be punished relative to degree and accountability, or someone righteous in both degree and accountability, be allowed to assume the guilty of the guilty and provide satisfaction for the guilty, who can appropriate this under the conditions necessary if they so choose.
Thus, God did not just "kill His Son," but sent His Son on a mission - which the Son volitionally was in agreement with - (John 10:17) and in which the sinless Son would take responsibility for all the sins of mankind, (1 John 2:2) becoming as it were "sin for us" (2 Cor. 5:21) - the iniquities of all mankind being imputed to Him - that those who, in repentant faith, appropriate this atonement are cleared of guilt in order walk in newness of life, while having recourse to forgiveness after that as they seek to follow their scapegoat savior. For your actions are always a result of what you are truly believing. As was foretold,
But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed. All we like sheep have gone astray; we have turned every one to his own way; and the Lord hath laid on him the iniquity of us all. (Isaiah 53:5-6)
Therefore, the Father did not simply "kill His Son," nor was it simply being crucified itself that was so loathsome that it brought the Son to sweat drops of blood (Luke 22:44) in agonizing anticipation of what would follow, that of drinking the metaphorical "cup" that He had to drink of, (Luke 22:42) but it was that of a spiritual sense, of becoming what He abhorred (I liken it to drinking raw stinking sewage), the very opposite that He loved in becoming abhorred, and therefore being treated as such in losing the unique communion with His Father, signified by darkness being upon the earth for 3 hours (Luke 23:44)
Indeed, actually dying, as He said "It is finished" (Jn. 19:30) and commending His spirit to His Father, was the least of His sufferings! However, it is the most precious substance, that of the lifeblood of the sinless scapegoat, that makes atonement for the most anti-life destructive thing, sin. (Lev. 17:11) It was who and what Christ did and became that made His blood atonement efficacious for all who would appropriate it by effectual repentant heart-purifying, regenerating, justifying belief, (Acts 10:43,47; 15:7-9; Titus 3:5; Romans 3:25) thus effecting the obedience of faith. Thanks be to God.
In contrast, your objection that the death of His Son was not necessary makes a mockery of justice, meaning there need not be any penalty for sin - which wrong choices have consequential effects upon others, varying in scope and degree, thus no satisfaction for it, just that of issuing pardons.
And as for choosing Light over Darkness, without this choice btwn contrasting realities then the ability to make choices is meaningless, while what man chooses is revelatory of what his really seeks. The Bible teaches those man is accountable relative to the level of Divine Truth given them, beginning with a good conscience and the light of nature - even if ignorant of the express revelation of writing - (Romans 2:14-16) - and rejection of that is in essence a rejection the Word of God, the Son, by whom comes Divine revelation, (John 1:9) while rejection leads to deception.
Conversely, and those who at some point seek to obey that Truth will be given more revelation, and if continually sought, leads to The Light, even Christ. (Matthew 6:21-23; Luke 8:18; Mark 4:24,25;John 12:35-48) Oh, and by the way he was just kidding when he “sacrificed” his son, cause he knew he would come back to life a couple of days later. Not much of a sacrifice, just a bit of magic, no?
Again, this objection flows from the ignorance of the nature of atonement, in which the sinless scapegoat did not just die, but died as bearing the sins of mankind, and not simply as one who was innocent in His own choices, as an infant is, and the scapegoat under the Law (Lev. 16) having all the sins of the people of God placed upon him, nor the goat that was slain as atonement, which prefigured the suffering srrvant of Is. 53) but as righteous, having faced the basic tests of pride, possessions and sinful pleasure that man faces, (1 Jn. 2:16) and prevailed over them, (Hebrews 4:15) even when tempted by the devil himself with being given all the kingdoms of the world - without the cross. (Matthew 4:8-10)
And thus this life reveals what man really wants, (Jn. 3:19-21) while as omniscient and omnipotent, God can and will make all to ultimately work out for what is Good, in the light of all that can be known. Which includes just punishment for eternal beings which manifest they wanted the opposite of God.
As for other alternatives here are some.
And why was that his only son? I thought we were all his sons and daughters. Are some of his sons more privileged than others?
While we are the offspring of God as being His creation - as beings able to defile ourselves and others by our choices, yet spiritually we do no belong in His family unless we choose Him over sin, which faith in His sinless Son signifies, (John 3:19-21; and as said, obeying the level of Divine light one has indicates seeking this. (Matthew 6:21-23; Luke 8:18; Mark 4:24, 25;John 12:35-48; Romans 2:14)
And thus some of God's creation are indeed more privileged than others, whether it be man over animals, or some humans being better at some things than others. Yet unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more. (Luke 12:48)
Souls receive life in themselves and are saved by effectual penitent, heart-purifying ("purifying their hearts by faith"), regenerating, justifying faith in the Sin-bearing, Atoning, Crucified and Risen Divine Son of God, (Acts 10:43-47, 11:13-18, 15:7-9; Titus 3:5) who saves sinners on His merit, (2 Cor. 5:21) thereby being made "accepted in the Beloved." (Eph. 1:6) For which faith is imputed for righteousness, (Romans 4:5) and is confessed/shown by baptism (Acts 2:38, 8:12, 36, 37) and following the Lord according to His word, by His Spirit, (Acts 2:38-47; Jn. 10:27, 28; Romans 8:13, 14) with repentance when convicted by conscience of not doing so. ((2 Samuel 12:7-13; Psalms 32:5, 6, 51:3; Hosea 5:15; 1 John 1:9) Glory and thanks be to God.
Which faith is in contrast to those who were never born of the Spiritor who terminally fall away, thereby forfeiting what faith obtained. (Gal. 5:1-4; Heb. 3:12, 10:25-39) - https://peacebyjesus.net/savedorlost.html
Why did God begot his Son?