Is it really necessary to obey God's commandments to be saved i.e. to have eternal life?

What do these Scriptures mean?🤔
Matthew 5:18–19 (AV 1873): For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled. 
19 Whosoever therefore shall break one of these least commandments, and shall teach men so, he shall be called the least in the kingdom of heaven: but whosoever shall do and teach them, the same shall be called great in the kingdom of heaven