Can you just go to church on Sunday morning and still expect to spend eternity with God?
No. Attending Sunday morning services for an hour while ignoring the gospel is not enough. The proof of belonging to God is whether the Holy Spirit dwells within you; if any man has not the Spirit of Christ, he is none of His. Eternity with God requires the Spirit, not outward religious dressing.
Les explains that the criteria and proof of salvation is whether the Holy Spirit dwells within a person. If He does, you are solid; if He does not, you are on thin ice. Les warns that people cannot just take these things in one ear and out the other, dress it up a little on Sunday morning for an hour, and then hope to spend eternity in the presence of their Creator—it is just not going to happen. Paul also warns that everyone will be judged by his Gospel: that Christ died, was buried, and rose again, and all will stand as lost or saved by what they have done with that Gospel.