Does the Bible specify how a Christian must be buried? I've heard it taught that believers should be buried with our feet facing East and our head facing West, since West is the direction of holiness, but I can't find this in the Bible.
As you mentioned, East and West can have associated meanings in eastern philosophy and in scripture. In the Bible, East is often associated with Satan, sin, judgment and the fallen world, while West is associated with the opposite concepts of God, holiness, salvation, and Heaven.
Perhaps for this reason, the practice of burying the dead with feet facing east has become a long-standing tradition crossing many religions and cultures, though it is not universally practiced. For example, many pagan cultures worshiped the sun in some form, therefore facing the direction of the rising sun (i.e., East) was the preferred burial position for ancient pagans.
On the other hand, Jews typically buried their dead facing west, because the tabernacle design required approaching the glory of God in the Holy of Holies by entering the tabernacle from east to west.
Christians adopted a practice of burying their dead facing east because the scripture teaches that at the Messiah's Second Coming into Jerusalem, He will approach from the East (see Isa 63:1; Zech 14:4; Matt 24:27). Therefore, Christians who believed they would be resurrected at the Second Coming of Christ gave instructions to have their bodies buried facing East so they might greet Jesus face-to-face at His Second Coming.
All of these practices are based in superstition and faulty theology, not on the Bible. Regarding Christian practice, there is no prescribed method for burial in the Bible nor even was the tradition consistent with scripture. The Bible teaches that believers will be resurrected at the Coming of the Lord for the Church (commonly called the Rapture), not at Christ's Second Coming to Earth. (For a complete explanation of the rapture, please listen to our Revelation Bible study.
Secondly, at our death our spirit goes to be with Christ, so our conscious self is not “in the grave” awaiting Christ’s return. Instead, we live with Him in the Heavenly realm while we wait for the resurrection:
2Cor. 5:6 Therefore, being always of good courage, and knowing that while we are at home in the body we are absent from the Lord —
2Cor. 5:7 for we walk by faith, not by sight —
2Cor. 5:8 we are of good courage, I say, and prefer rather to be absent from the body and to be at home with the Lord.
Paul contrasts being “at home in the body” with being “at home with the Lord.” Being at home in the body means being alive on the earth, while being at home with Christ means our body having died and our spirit having gone to be at Christ’s side in Heaven. According to Paul, when a believer dies his spirit goes into the presence of the Lord, while his earthly body remains behind buried.
Therefore, there we will not experience our future resurrection from the perspective of an earthly body lying in the grave. On the contrary, we will experience it from Heaven, as our spirit accompanies Christ back to the clouds, as Paul described above in 1Th 4:15-17. We will witness our own resurrection from the perspective of our spirit in the clouds.
Thirdly, those who do remain alive on earth awaiting the resurrection do not meet Christ on earth in a cardinal direction. Rather, scripture teaches that at the resurrection believers remaining on earth are "caught up" to meet Jesus in the clouds:
1Th. 4:15 For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord, will not precede those who have fallen asleep [died].
1Th. 4:16 For the Lord Himself will descend from heaven with a shout, with the voice of the archangel and with the trumpet of God, and the dead in Christ will rise first.
1Th. 4:17 Then we who are alive and remain will be caught up together with them in the clouds to meet the Lord in the air, and so we shall always be with the Lord.
Therefore, the direction of movement to Jesus is upward, not East or West.
Finally, the new body isn’t constructed using the material of our original earthly bodies. Paul says that our new bodies will be constructed from entirely new materials:
1Cor. 15:42 So also is the resurrection of the dead. It is sown a perishable body, it is raised an imperishable body;
1Cor. 15:43 it is sown in dishonor, it is raised in glory; it is sown in weakness, it is raised in power;
1Cor. 15:44 it is sown a natural body, it is raised a spiritual body. If there is a natural body, there is also a spiritual body.
1Cor. 15:45 So also it is written, “The first man, Adam, became a living soul.” The last Adam became a life-giving spirit.
1Cor. 15:46 However, the spiritual is not first, but the natural; then the spiritual.
1Cor. 15:47 The first man is from the earth, earthy; the second man is from heaven.
1Cor. 15:48 As is the earthy, so also are those who are earthy; and as is the heavenly, so also are those who are heavenly.
1Cor. 15:49 Just as we have borne the image of the earthy, we will also bear the image of the heavenly.
Paul says that our second body will be of a “heavenly” material rather than an earthly material. This change is necessary because the earth is under a curse (see Genesis 3). Therefore, the positioning of our earthly body in the grave (or even if we are cremated) will have no bearing whatsoever on our eventual resurrection.
In summary, burial traditions are based in superstition, not a proper view of scripture. For the Christian, we have liberty to dispose of our earthly body as we desire. The direction of burial is irrelevant. At death our current body returns to dust, while our spirit lives on in the company of Jesus. One day we will receive a new eternal body, but our new body won't originate from the burial location or material of our old body. The Lord creates a new heavenly body for us.