Yes, Messiah is the greatest blessing as is the indwelling Holy Spirit. That does not change the fact that the Sabbath rest is a blessing as well. Keeping the Sabbath does not make one religious. It makes one obedient and keeps one from sinning against YHWH.
Acts 15:24 was an incomplete summarizing of Acts 15:1:
And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved.
No, that's not me. I'm the guy in Isaiah 58:13-14;
If thou turn away thy foot from the sabbath, from doing thy pleasure on my holy day; and call the sabbath a delight, the holy of YHWH, honourable; and shalt honour him, not doing thine own ways, nor finding thine own pleasure, nor speaking thine own words:
Then shalt thou delight thyself in YHWH; and I will cause thee to ride upon the high places of the earth, and feed thee with the heritage of Jacob thy father: for the mouth of YHWH hath spoken it. :)