What is the ruling on saying: "Allah is with us" and "I have no Lord," and do these fall under mocking Allah?

If the speaker intends by the phrase "Allah is for us" that Allah is a helper and protector for Muslims, then there is no harm in it. However, it is better to say "Allah is our Protector (Mawlana)" or "Allah is with us" or "Allah is our Lord," based on His (the Most High) saying: "Indeed, Allah is with us" and "Allah is our Lord and your Lord," and the hadith: "Say: Allah is our Protector, and you have no protector."

As for the statement "I have no Lord," this is a negation of Lordship, which is disbelief (kufr), and its utterer must repent.