Galatians 5:4

The same great and solemn truth is repeated in different terms. "Christ shall profit you nothing" = "a debtor to do the whole law" (and therefore under a curse in consequence of failure) = "Christ is of no effect unto you" = "ye are fallen from grace". Similarly, "if ye become circumcised" = "every man that submits to circumcision" = "justified by the law".

Christ is become of no effect Lit. -ye were cut off from Christ", brought to nought as regards any benefit accruing to you from Him.

are justified by the law i.e. seek to be justified by the law.

ye are fallen Probably, -ye are cast forth" (like Hagar and her son), banished from grace. The Apostle is not here stating anything as to the possibility of recovery after such a relapse. His object is to make it quite clear that if righteousness (or justification) is sought in the law (i.e. by works) it involves the forfeiture of grace, and the forfeiture of grace is ruin.