The way God was interpreted varied with time, even if that sounds painful to the ears of some people. To give a simplification, taking the big 3 Abrahamic faiths in account:
Canaanite tribes worship a pantheon of gods, including El, the High God. One such tribe decides to break off by worshipping Yaweh, the thunder god of the neighboring mountain tribes. Yaweh's counterpart in Canaanite religion is Baal, but Israelites (the followers of El) decide to merge El with Yaweh, and give Yaweh's name a different writing and interpretation - YHWH. The Torah was made of several sources and it is pretty obvious that different sources are not ancient to the same degree and that, theologically, it is a little messy. YHWH is El and talks to Abraham like a friend, but then YHWH is YHWH and he's back with a vengence. He reveals himself to Moses and leads him to curse Egypt with several plagues to make His name known and feared, then to lead the Israelites back to Canaan (although this is the Biblical point of view - archeologically, nothing indicates the Israelites ever left Canaan). He arbitrarily decided to be Israel's guardian god and to lead them to victory in warfare over their enemies. And all of this without forgetting that the existence of other deities is very much implied throughout the oldest texts (parts of the Torah, parts of the Psalms).
Around the time of the Babylonian exile, that is when the idea of YHWH as not just a god of justice, but the only God to have ever existed, has begun and as such becoming the "real" birth of Judaism, about 6 centuries before Jesus' birth. The old covenant made with Moses was found (how different it was from the final version we have, if it wasn't even fabricated to begin with) and confirmed that YHWH wasn't the great guy leading Israel to victory, but a jealous God who would not tolerate them worshipping other deities or leaving the Mosaic law behind. That is also when prophets such as Jeremiah portrayed God as an all-powerful figure, omnipotent, all-just, judging over all nations and not just Israel, and being more than willing to use other nations to destroy Israel if it were necessary to bring moral order.
This is the interpretation of YHWH that remained until the birth of a certain Jesus guy (I know, more like Yeshua, don't bother with details). We know that story too well: he claimed to be the messiah who was predicted by several major prophets in Judaism. But because he did not fit the literal prophecies of the Israelite tradition and because he ended up being executed anyway, few people paid attention except for a small cult that would celebrate him as the messiah. The overall result of the apostles and Paul's teachings and traveling became a new, organized religion that turned out philosophically and theologically different from Judaism. Strongly influenced by Greek philosophy and theology, the Church would end up developping concepts such as the Trinity, natural law, etc. As for God, he went from being El the nice guy to Yaweh/YHWH the not so nice guy to YHWH the all-great ruler past the concepts of "good" or "bad", who only wants "justice", to Jesus being God and the Father being God and the Holy Spirit being God and God being a trinity, three different persons making one single God. The Father can be assimilated to the "essence" of YHWH, distant, judging and unknown, the Son is Jesus who preached love and tolerance for all and the Holy Spirit is the wind of prophecy, she can be assimilated to the "depiction" of YHWH, or YHWH as understood by the prophets. The Holy Spirit is in all Christians, it is sometimes assimilated to the personified Wisdom from a couple of the OT's writings as well.
The Catholic Bible was finally compilated in the 5th century (or so). During the 7th century, Muhammad began preaching about his own visions, or rather messages, from God (given to him through the Holy Spirit). There are many differences with Christian doctrine (even more noticeable because, unlike with Christianity which was founded by Jews, Muhammad was a pagan before he started preaching), but to make things simple: the Father is God (Allah). The "Son" isn't a thing, Jesus was only a prophet but was the messiah. And the Holy Spirit is Gabriel, an angel and not God either. Apocalyptic messages with horrifying visions of eternal burning, consumption of boiling water, etc. in Hell are found next to messages about warfare (as the law of talion that Jesus abolished gets re-established) which are found next to messages about practicing charity, giving women more rights in the family, practicing self-restriction, etc.
** TL;DR **
The interpretation of God has constantly changed over time due to it not meeting social difficulties anymore. From a friendly God (El pretty much got along with everyone from what we could gather), to a God of warfare, to a God of objective and impartial justice, to a God who seeks love, justice and wisdom, to a God who seeks submissiveness.
It's not Him who's making things confusing, it's us.