God does miracles in our lives because of our faith in what we have from God the Father by what Jesus did for us. God never gives us miracles because of how much we obey the Law. No, it is it because of what we do, but it is because of what Jesus did for us. Every miracle we receive from God is always entirely by his grace and entirely independent of our good works.
Paul is saying to the Galatians in Galatians 3:5, that God works miracles among them, independent of their works, and regardless of if they obey the Law of God properly or enough.
He is explaining to them, that it is by the Holy Spirit and faith in God that we receive the miracles from God, no matter if we obey the Law, because it is by grace from God that those miracles happen, and not if we deserve them by obeying the Law. It is entirely the work of God and his grace and Holy Spirit in us, that does the miracles, regardless of what commands from the Law we obey.
It is not dependent on us to have miracles from God, but it depends on his grace and power in our life. Our only role, is to accept all that God the Father has done for us through the death and resurrection of our Lord Jesus by faith, and apply it by faith in our life, in order for us to see the miracles God does.