how exactly do i follow the spirit of the law over the letter and is it biblical to do so?
Here are some things which are Biblical >
"we who first trusted in Christ" > in Ephesians 1:12.
"'Take My yoke upon you and learn from Me, for I am gentle and lowly in heart, and you will find rest for your souls.'" (Matthew 11:29)
"If anyone desires to come after Me, let him deny himself, and take up his cross daily, and follow Me." (in Luke 23:9)
Now, a common issue is if we "keep the Sabbath", or are no longer required to do so. How would you keep it "in the Spirit"? It is not intended only for outwardly not working.
"Let every man remain in his place; let no man go out of his place on the seventh day." (in Exodus 16:29)
From this, I consider God means you stay in your place . . . at home to rest . . . not to go out doing things, even like church. But you rest. And it is time for prayer, not for TV and games and catching up on chores . . . but rest in prayer with God so now you are the right way to be, all through the week > prayerful and resting in Jesus while working and other things. And when you get away from this, into rat-racing . . . take a pit stop and stop that anti-rest stuff, then do what God has us doing in His peace >
"And let the peace of God rule in your hearts, to which also you were called in one body; and be thankful." (Colossians 3:15)
Or else, we are not keeping the Sabbath, but forsaking it by not staying in the blessedness of Jesus that we had on the Sabbath.
And one part of keeping our rest is >
"Do all things without complaining and disputing," (Philippians 2:14)
And >
"Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice." (Ephesians 4:31)
"And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you." (Ephesians 4:32)
So, we stop our anti-rest stuff, in order to get into how we can be loving, instead, with God . . . how this is possible with God.
The Sabbath is given, that everyone "may be refreshed" > in Exodus 23:12. So, this is for everyone > you love others as yourself, by helping and welcoming anyone else to also have refreshing rest which is in Jesus > "you will find rest for your souls" if and however you obey Jesus . . . all the time, by the way, not only on Saturday.
"Whoever does any work on the Sabbath day, he shall surely be put to death." (in Exodus 31:15) So, you "might" get into a problem by doing this by the "letter".
God was "refreshed" on the seventh day. And He wants you to be "refreshed". (Exodus 23:12) This would be in sharing with Him in us refreshing us so we are sweetly sharing with Him ! ! ! There is the love meaning of whatever God's word says. And this does not need to stop at the end of the Sabbath. But - - - however we get blessed with God in prayer and resting in Him, on the Sabbath . . . this is our model and example and sample of how to be with God all through the week . . . so we are not doing our own works, and are resting in doing His.
"that your male servant and your female servant may rest as well as you" > in Deuteronomy 5:14. So, keeping the Sabbath is a "love your neighbor as yourself" thing, including loving your servants as yourself by making sure they also do no work so they may be refreshed.
And, at any time, love others by not just using them; help and encourage others to have rest and peace in all they do for you and with you.