I don't think Christians realize what they are doing when they insist on clinging to some portion of the law, attempting to mix it with grace. As far as that goes, not even the power of God can help you. The Holy Spirit will not help you attain righteousness under the law. God will not be unfaithful to the Covenant he made by and through his Son, Jesus.
By clinging to tithing or any bit of the law, you are disqualifying your High Priest, Jesus. Tithing and the whole of the law is under the Levitical Priesthood. Now, what is the requirement of being in the Levitical Priesthood? Is it not to be from the line of the patriarch Levi? Yet we see Jesus is not from the tribe of Levi, but of Judah! The law would disqualify Jesus as your High Priest! You don't know what you're saying when you insist on Galatian theology that says "Yes, its grace, but you need to do your part." You're talking out of your rear.
You're saying "Yes, Jesus saved me, but I can save myself too." You're doing exactly what Paul warned against doing in his letter to the Church in Galatia. You are cut off from Christ and found to be under a curse! You idiot! "Having begun by the Spirit, are you now being perfected by the flesh?" In Americanese, "Having been saved by grace, are you now trying to finish the job by works?" This is a salvation that is, "by faith from first to last."
You readily accept grace for initial salvation and then you play the whore by deserting him and turning to yourself.
You say one thing and then contradict it! You say we're saved by grace, but if we sin, we lose it. You say God makes me righteous apart from the law, but if I disobey the law, I become unrighteous.
Am I encouraging sin? Don't be stupid. But if I go to hell clinging to this promise of grace, then so be it.