I personally believe it is not about religious practises or affiliations that the Lord will look out for on the final judgment. The key to salvation is faith in God though the acceptance and confession of Jesus Christ as Lord and Savior.
John 14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.
It is Christians that preach the message of Jesus'death and ressurection and it's significance to mankind. So we believe that when He appears, we shall be like Him and He will welcome us and we will reign with Him forever.