Well, yes and no.
Non-Jews are actually forbidden to observe Shabbat (at least with regard to the prohibitions;
It depends on whether one follows the dictates of the Jewish tradition or not. I would say that biblically speaking those who join themselves to Israel through Christ become partakers of the blessings promised to Israel, including the blessing of the sabbath.
Eph 2:12 That at that time ye were without Christ, being aliens from the commonwealth of Israel, and strangers from the covenants of promise, having no hope, and without God in the world:
Eph 2:13 But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ
Shabbat was given to Israel shortly before they arrived at Mt. Sinai when they were told not to gather man ("manna") on the Seventh Day of the week. However, the 'Avot (Abraham, Isaac, and Jacob) had already intuited all the commandments of the Torah according to the Sages.
The article presents a number of interesting passages about sabbath observance even before Abraham.
Non-Jews are actually forbidden to observe Shabbat (at least with regard to the prohibitions;
It depends on whether one follows the dictates of the Jewish tradition or not. I would say that biblically speaking those who join themselves to Israel through Christ become partakers of the blessings promised to Israel, including the blessing of the sabbath.
And there's where you jump the track.
"Biblically speaking" and "chr*stianity" simply don't go together.