When God was preparing the people to bring them into the land which He had promised to give them, He warned the people that in order to inhabit the land, they would need to obey God and keep His commandments. If they disobeyed, God would bring curses upon the people, and if they continued in their sins through all of these curses, they would be exiled among the nations. While the literal interpretation of the effects of the peoples' sin is only relevant to the physical inhabitation of the land of Israel, the underlying truth remains the same for every believer in Yeshua who has been grafted in.
Moses begins by telling the people, "Be silent and listen, O Israel! This day you have become a people for the Lord your God. You shall therefore obey the Lord your God, and do His commandments and His statutes which I command you today" (Deuteronomy 27:9-10). By putting His name upon the people of Israel, God chose them to be a special nation of His own possession. Because of this, they needed to obey Him and do His will in order to continue to be blessed according to His will.
We see that if they do not obey God and keep His commandments, then the people will be cursed: "'Cursed is he who does not confirm the words of this law by doing them.' And all the people shall say, 'Amen'" (Deuteronomy 27:26). If by transgressing the Torah the people would be cursed and eventually exiled from the land, were the people of Israel doomed from the start? We know that it is not possible to never sin. Was God simply setting the people of Israel up to fail? "But it shall come about, if you do not obey the Lord your God, to observe to do all His commandments and His statutes with which I charge you today, that all these curses will come upon you and overtake you" (Deuteronomy 28:15). Was God sitting in heaven waiting for them to make a mistake so that He could punish them?
No, for we also know that God is merciful and He blesses those who obey Him to the best of their ability while not trusting in their own actions to gain any merit in the sight of God. We see through Scripture that in the times when Israel has a leader who removes the idols from the land and trusts in God, the land and the people are blessed. "All these blessings will come upon you and overtake you if you obey the Lord your God" (Deuteronomy 28:2). This doesn't mean that during these times nobody in the nation of Israel committed any sin at all, but it means that as for the most part the people were making a genuine effort to put their trust in God and obey Him.
While in some Christian circles we tend to shy away from the thought of meriting any type of reward or punishment based on our obedience to God, we see that this theme is carried over into the New Testament. Yeshua (Jesus) tells us near the end of Revelation, "Let the one who does wrong, still do wrong; and the one who is filthy, still be filthy; and let the one who is righteous, still practice righteousness; and the one who is holy, still keep himself holy. Behold, I am coming quickly, and My reward is with Me, to render to every man according to what he has done" (Revelation 22:12). Here we see that the way one has behaved and the deeds he has done play a large role in how one is determined as righteous or unrighteous, and the measure of a person's deeds will be returned to him in some way.
This is not in conflict with the concept of salvation as a free gift to those who believe. The same mouth that said, "The Son of Man is going to come with his angels in the glory of his Father, and then he will repay each person according to what he has done," also said, "For God so loved the world, that He gave His only begotten Son, that whoever believes in Him shall not perish, but have eternal life." The belief seen throughout the Scriptures is never a belief which is merely an assent to the existence of God and the sacrifice of His Son. It is a living and active belief which results in obedience. As James tells us, "Show me your faith without deeds, and I will show you my faith by my deeds" (James 2:18).
We as believers in Yeshua have become joined to Israel in being a people for the Lord our God. As such, we are called and expected to behave in accordance with God's will for us. This doesn't mean that we resort to a legalistic view, where salvation is only attainable by meeting a certain standard of obedience. But God has told us that we will be rewarded if we continue to obey Him in love, not because we are relying on our deeds to gain us a reward, but because it is through our actions that we reveal what is within our hearts. May God bless us all as we seek to know Him and His Son through every part of our lives.