People are damned for their sins. they are saved solely by the atoning sacrifice of Christ on the cross for their sins. If you think that there is anything you can do to save yourself from your sins or if you think there are additional requisites to forgiveness of your sins, such as "obedience to the laws and ordinances of the (LDS)gospel" or baptism by the LDS Church or anything other than the Blood of Jesus Christ, then you are denying the sacrifice of Jesus for your sins and hence you are still under the condemnation of your own sins.
Now in order to believe in Jesus you need to believe in THE TRUE Jesus and not some counterfeit Jesus. The Mormons believe that Jesus is literally the Brother of Satan and that Jesus was not God from all eternity and that Jesus did not create everything, etc. This is not the Jesus that is revealed in scripture. the Jesus revealed in Scripture is the ETERNAL WORD OF GOD.
Hence if you buy into the Mormon doctrine, then (IMHO) you do not believe in the Jesus that died on the cross and your belief will not be effective in bringing about any atonement for your sins.