To believe the Gospel is to believe that Jesus Christ the only begotten Son of God died for your sins and rose again after 3 days, ascended into heaven, and is to come again granting you everlasting life by your faith in Him.

This also makes you a Christian and because of this a Christian is born again and walks in newness of spirit not in the oldness of the letter of the law.

Let me give you an example of the difference between a Christian and a Legalist...

It's the Sabbath and it is written to not do any work on the Sabbath yet one of your lambs have fallen in a ditch.

Legalist = Can't do anything, it's the Sabbath, it would be a sin.

Christian = Saves the lamb and in so doing did not sin because to the Christian (and to God) the Sabbath was made for man not man for the Sabbath. Technically though the letter of the law was broken.

I can give more examples if you wish...

If you actually studied the book of Romans you would understand these things...

"There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit. For the law of the Spirit of life in Christ Jesus hath made me free from the law of sin and death. For what the law could not do, in that it was weak through the flesh, God sending his own Son in the likeness of sinful flesh, and for sin, condemned sin in the flesh: That the righteousness of the law might be fulfilled in us, who walk not after the flesh, but after the Spirit." -- (Romans 8:1-4)