Do gay Christians who are in relationships with the same sex just dismiss what the Bible says about it but believe in some of the other parts of the Bible and consider themselves still a Christian? I know I dismiss parts in the Bible and I'm still a Christian.
I think it is a matter of love of what Jesus Christ did for us on and through the Cross.
For and example:
Eph 4: 28 Let him that stole steal no more: but rather let him labour, working with his hands the thing which is good, that he may have to give to him that needeth.29 Let no corrupt communication proceed out of your mouth, but that which is good to the use of edifying, that it may minister grace unto the hearers.
So there are Christians who have to go beyond what they use to do, whether corrupt communication or even robbing. Love desire to be more like Jesus.
Romans 6:12-14 King James Version (KJV)
12 Let not sin therefore reign in your mortal body, that ye should obey it in the lusts thereof.
13 Neither yield ye your members as instruments of unrighteousness unto sin: but yield yourselves unto God, as those that are alive from the dead, and your members as instruments of righteousness unto God.
14 For sin shall not have dominion over you: for ye are not under the law, but under grace.
So, again, it is a matter of changing for love sake and yielding to what God wants and not what we want. It is a matter of whether or not Jesus is truly the Lord of our lives.