THE SINGLE MOST IMPORTANT MITZVAH OF ALL of Scripture is to trust in Yeshua as your LORD and Savior. Everything else centers on this. The two "great commandments" are the Ve'ahavta ("Love the LORD with all your heart") and the obligation to love others as yourself (Matt. 22:36-40). These two commandments presuppose, however, that: 1) you believe that the LORD is real, personal, loving, and accessible, and 2) you are in fact able to love the LORD and others in the truth. As I mentioned recently, however, apart from genuine spiritual rebirth and the new life imparted through Yeshua (i.e., chayim chadashim: חַיִּים חֲדָשִׁים), it is literally impossible (οὐ δύναται) to fulfill these commandments. Those who are "in the flesh" cannot please God (Rom. 8:8). Indeed, the principle (νόμος) called the "law of sin and death" (תּוֹרַת הַחֵטְא וְהַמָּוֶת) is invoked whenever someone attempts to draw close to the LORD apart from faith in His appointed Sacrifice and Mediator for sin. The idea that your "good deeds" can merit access to the LORD's Presence and favor is ultimately the negation of the cross. The Apostle Paul warned that those who perverted the message of the gospel by adding any form of "works of law" (מַעֲשֵׂי הַתּוֹרָה) were under a divine curse (Gal. 1:8-9). Yes, it's that serious of an issue...
וְצַדִּיק בֶּאֱמוּנָתוֹ יִחְיֶה
ve·tzad·dik be·e·mu·na·to yich·yeh
This small phrase, consisting of only three Hebrew words, is the central axis upon which our salvation turns, since it distills the requirement that we are justified by our faith in God's righteousness (צִדְקַת אֱלהִים) and not by "works of righteousness (מַעֲשֵׂי הַצְּדָקָה) which we have done" (Titus 3:5). Regarding the righteousness that comes by faith and its relationship to the works of the law, Paul writes: "To the one who does not work (τῷ μὴ ἐργαζομένῳ) but trusts in him who justifies the ungodly (πιστεύοντι δὲ ἐπὶ τὸν δικαιοῦντα τὸν ἀσεβη), his faith is counted as righteousness" (Rom. 4:5).
מִי אֲשֶׁר־לוֹ הַבֵּן יֶשׁ־לוֹ חַיִּים
mi a·sher lo ha-ben yesh lo chay·yim
Whoever has the Son has life; and whoever does not have
כִּי הַיְשׁוּעָה מִן־הַיְּהוּדִים הִיא
ki ha·ye·shu·ah min ha·ye·hu·dim hi