As I became a teenager though, my Sunday school teachers started adding a disclaimer next to "all-loving." I started realizing that he is only all loving if you are a Christian heterosexual man or woman who follows every commandment to a tee.
This is one of the things about mainstream Christianity that turns off some people. Only about 1/3 of the world's population calls itself Christian. That means that, even taking them all at their word, by mainstream theology 2/3 of the world is condemned to eternal damnation. A lot of people have trouble believing in that.
Mainstream conservative Protestant theology might say that. Catholic or Eastern Orthodox theology does not.
If any of those 2/3rds are saved, they are saved through the merits of Christ. Perhaps God chooses to save some without formal church membership, perhaps not. In any case, we are called to preach the Gospel to everyone, not to theorize about the fate of those who cannot or will not hear it.
A large majority of humanity being condemned is explicitly stated by Christ: "Enter by the narrow gate; for wide is the gate and broad is the way that leads to destruction, and there are many who go in by it. Because narrow is the gate and difficult is the way which leads to life, and there are few who find it." -- Matthew 7:13-14
TBP wrote: "A lot of people have trouble believing in that (2/3 of mankind doomed)."
Nevertheless, that's what the Bible teaches. Whether man believes it's going to happen or not is totally irrelevant.
If nothing else, the fact that 2/3 (or more) are doomed should motivate us Christians to witness more.